A Brutal Murder, a Wearable Witness, and an Unlikely Suspect

As Tony Aiello entered his nineties, he had false teeth, an artificial hip, and an artificial knee. He gripped a walker to hoist himself out of bed. Stiff in the back, he had contraptions to help him pull on his pants and socks, along with a shoehorn to slide his feet into velcro-strapped shoes. He had hearing aids and a pacemaker with a defibrillator for his triple-bypassed heart. He would read recipes in the living room and forget the ingredients by the time he reached the kitchen. Arthritis stiffened the fingers that had served him for decades as a deli butcher, so he cut food with scissors. He took blood thinners for his congestive heart failure. The slightest nick while pruning trees in the yard would make him bleed until his wife, Adele, would, as he put it, “patch me up.” After losing an inch or so to age, Tony stood 4’11”.

Still, Tony would brag, “Nobody believes that I’m 90.” He could do anything—“a little slower.” Perhaps that was just Tony being Tony. People who’d known him for decades said he’d always had “little man syndrome.” But maybe there was something to the bravado. Neighbors said that not so long ago, Tony seemed hale—a stocky figure walking down the sidewalk in a tank top, like a pint-size, sure-stepping Marlon Brando. He was gutsy too: When he was about 80, he met Adele Navarra while they were in line at the Save Mart meat counter and asked her to coffee the same night. He bought two dozen roses for the occasion.

Both Tony and Adele were widowed, and before long they married. Adele was two years Tony’s senior, but people marveled at how sharp she was. She moved into Tony’s house in the Berryessa neighborhood of eastern San Jose, California. By chance, her daughter, Karen, lived just two blocks down the street. Once, when Adele fell in the yard, a neighbor who came to her aid noticed that Tony seemed just as doting as could be as he helped her back into the typical ranch home on a typical San Jose block where, by all appearances, he’d lived a rather typical life for the past 50-plus years.

Then, on September 14, 2018, a coroner’s investigator came to the house and broke anguishing news: Adele’s daughter, Karen, had been found dead.

Karen was 67 and lived alone with her two cats in a house on Terra Noble Way. She worked as a pharmacy tech at a San Jose hospital, and when she didn’t show up for work, a coworker stopped by to check on her. The front door was unlocked, and, once inside, the coworker found Karen’s corpse in a chair at the dining room table, her legs stretched out, her head slumped over the chair’s back, bloody from bash wounds that an attorney would later say “destroyed her identity.” Her right hand clutched a Flint kitchen knife with an 8-inch blade. Her throat was slit, twice.

The investigators who arrived saw no telltale spatter of a throat-slashing; the slice had happened after she was already dead. In fact, it looked not only as if the scene had been staged but ham-handedly so, without a clear idea of the faux plot. The knife in Karen’s hand seemed to suggest suicide, yet the knocked-over chairs indicated a struggle. Her bedroom and kitchen drawers were open or on the floor as if ransacked, but the drawers were neat, their contents intact, with cash, jewelry, and electronics still in the house, financial documents on the kitchen table.

The criminal oversights didn’t end there. As Karen’s body was unzipped from the body bag and laid out at the morgue, the coroner took note of a black band still encircling her left wrist: a Fitbit Alta HR—a smartwatch that tracks heartbeat and movement. A judge signed a warrant to extract its data, which seemed to tell the story Karen couldn’t: On Saturday, September 8, five days before she was found, Karen’s heart rate had spiked and then plummeted. By 3:28 in the afternoon, the Fitbit wasn’t registering a heartbeat.

Police also collected video from a neighbor’s Ring surveillance camera that pointed in the direction of Karen’s house. The footage showed that before and after 3:28 pm, a gray car was parked in her driveway. That afternoon, a Toyota Corolla of the same color had shuttled over to her house with fresh-from-the-oven biscotti in a ziplock bag and slices of foil-wrapped pizza on a paper plate—a surprise treat from the driver: Karen’s 90-year-old stepdad, Tony Aiello.

In late January, Tony Aiello was pushed into a Santa Clara County courtroom in a wheelchair. Watching him cross the room from the front row was Adele Navarra Aiello, her walker parked in the aisle beside her. She opened her mouth, apparently overcome for a second, before collecting herself. In her nineties, Adele presents an elegant figure with short, gray hair, gold hoop earrings, pink blush, and a long brown cardigan. Tony’s daughter, Annette Aiello, a 61-year-old with wavy, black hair and her father’s squared-off shoulders, sat next to her, making notes on a legal pad. She occasionally showed these to Adele, who otherwise looked directly at Tony with closed-lip Mona Lisa inscrutability.

Based in large part on the data from the Fitbit and the neighbors’ surveillance camera, Tony had been arrested and charged with murder. He’d been held for four months in county jail awaiting trial and wore a red Department of Corrections shirt, loose civilian khaki pants, hot pink socks, and flip-flops because the jail couldn’t find shoes that fit. His pointy nose and a frame that nearly matched the dimensions of the wheelchair lent him an elfin quality.

Waiting for the hearing to start, he shot Adele an air kiss and massaged his arthritic knuckles one by one. He began to cry, plucking a tissue out of his chest pocket to blot the tears. Still, he seemed to try to cheer up his wife, theatrically raising his handcuffed, clasped hands and twiddling his thumbs in her direction as if lampooning himself—look at me still doing this, even here!—and sent Adele another kiss. The third time, she sent one back.

The hearing, at which the lawyers discussed when Karen’s autopsy report would be finished, did not last long. In the hallway afterward, a woman in a puffy jacket who’d also been in the courtroom approached Adele. She introduced herself, saying she’d worked with Karen decades earlier. She told Adele she looked marvelous. Adele smiled and said, “I’m 92.”

Old acquaintances and neighbors were abuzz, wondering why Adele was standing by her husband. (“If you killed one of my children, you’d have to prove to me you didn’t do it,” one told me.) But if the air kisses hadn’t shown it, Adele made it clear to Karen’s former coworker how she felt. “My husband is such a sweetheart,” she said plaintively. “They got along so well.”

Looking at Adele, the woman warily mused, “That’s just strange. That’s very strange.” Adele didn’t say it then, but she believed the murderer was still at large, and no fancy heart-tracking device was going to change her mind.

Anthony Vincent Aiello was born in Chicago in 1928, one of seven children. His family moved back to Sicily when he was a toddler, and after fifth grade he left school and started helping out in the family’s olive oil factory. In his late teens, he heard murmurs about being drafted into the Italian army. “Within a week, I was on a boat” back to the US, he said. He served in the US Army during the Korean War and afterward settled in San Jose, where his sister lived.

Tony found a job at a Del Monte pickle factory, got married, and later joined his brother-in-law to run a small grocery store on a rural road serving the local Italian and Portuguese farmers. While a family member says he was always a droll jokester with a “sparkle in his eye,” some people who knew him said he could be overbearing: “He was superior, and the boss.” One woman who worked for him as a teenager remembers thinking he was “creepy.”

The Aiellos had two kids, and by the late 1960s they were able to buy a home for about $37,000. Sprawl was fast churning orchards into suburban enclaves like theirs, and after his grocery was torn down to make way for a bigger road, Tony opened a deli in a strip mall an eight-minute drive from his house.

The whole family pitched in, and Tony, dressed in a white apron, presided over a long display case filled with lasagna-to-go and deli meats. He would chat with customers under the hanging mortadella and prosciutto. “He was a scrappy kind of guy, a don’t-mess-with-me kind of guy,” one regular remembers. Over the years, Tony lost most of his native Italian and would sprinkle his English, a language he’d only started speaking as a teenager, with movie-like quips—“You betcha” and “What’s up, doc?” He and his son, Tony Jr., started a towing business in the 1980s. “I love to work,” Tony would later tell interrogators. For a hobby, he hunted deer and boar; the walls of his converted garage were mounted with taxidermied game heads.

A 10-minute drive from the deli, Adele and Dominic Navarra lived with their two children, Stephen and Karen, in a ranch house in a subdivision called Warner Heights. Dominic, too, had his own business, a pharmacy, where Karen—people called her Cookie—took prescription orders, her hair pulled back into a long brown ponytail. She was pleasant, reserved, “the kind of girl you could tell a secret and she wouldn’t tell anyone,” said Therese Lavoie, who remained friends with Karen through their twenties. Lavoie said Karen’s brother, Stephen, was the outgoing one—much like their “jovial, larger than life” dad—while Karen took after Adele. “They were like the perfect family,” added Lavoie, who sometimes visited the Navarra home or went for a spin in Karen’s sporty Volkswagen Karmann Ghia. Karen studied science at nearby San Jose State University for three years, moved into her own apartment, and became a pharmacy tech at a regional hospital.

In the 1970s, Lavoie recalls, Stephen died in a motorcycle accident, an event that “changed them all, I think,” she said. “If Karen had even thought about having a future with a family, after that, I think she really wanted to take care of her mom and dad.” Dominic died in 1996. About a decade later, Karen inherited her grandmother’s home on Terra Noble Way. A few years later, in 2010, Adele married Tony in a City Hall ceremony, and Adele moved into Tony’s place, a cream-colored house with a garden of basil and tomato plants.

When Tony bought his house in the late 1960s, Berryessa, abutting the Diablo Range foothills, was a new, sparse neighborhood of mostly one-story homes with small front yards. Over the years, most of the original buyers sold to people attracted to the competitive schools and tech industry jobs. The Aiellos were living in Silicon Valley, but Adele said she only knew a little about computers and Tony said he knew “zero.” A four-bedroom ranch house that was once a first step into the middle class sells for more than $1 million. Neighborhood Watch signs in windows, porch cameras, and security signs speared into green lawns suggest an air of distrust around Berryessa’s manicured edges. Remaining old-timers say they don’t really know the younger set, and one neighbor complains of the commuter hive’s lack of neighborly graces: “They come in, shut their garage door, and go in their house.”

According to Adele, Karen used to say she was “the loner of the family,” her life revolving around work and home, where she cared for her cats and grew roses in her yard. As far as Adele knew, her daughter hadn’t seen anyone romantically in years. (And, it seemed, contentedly so: A coworker once heard Karen say, “Thank God I’m single. I don’t have to deal with all those problems.”) Karen and Adele talked on the phone every couple of weeks, and Adele kept a spare set of keys to her daughter’s house.

Karen, who was 5’5″ and about 170 pounds, seemed physically strong to her mother. She did a lot of walking on the job, pushing medicine-dispensing machines across the sprawling hospital where she’d worked for more than 40 years. She’d recently started wearing a Fitbit to track her steps. Adele described her as caring, taking shifts for coworkers who had family commitments. When an old acquaintance ran into her at CVS, she noticed that Karen was still wearing her ponytail, now graying, and was as gentle and pleasant as ever.

A few months before her death, Karen told her mother that she saw a man watching her from across the street and worried that he might be spying. After that, she started driving straight into her garage and sealing the door behind her. Around the time authorities believe Karen was murdered, at least two neighbors say they heard screams, possibly a cry of “Let go of me!” Neither neighbor called the police.

When the coroner’s investigator broke the news of Karen’s death to Adele and Tony, she held back the gruesome details, telling the couple Karen had suffered head injuries that they were still looking into. Later, she noted to the police that while Adele, seated at the kitchen table, seemed in shock, Tony walked in and out of the room and fetched Adele a tissue.

Shortly after the investigator left, Tony headed to Karen’s house, where the police were still combing through evidence. Seeing an officer standing guard outside, Tony asked if he could collect Karen’s mail. Tony called Karen “an angel” and asked the officer, “Why would someone do something like this?”

When two police detectives arrived at the Aiellos’ house later that afternoon to interview the couple, Tony opened the drapes and saluted them from inside the window with a wide grin. As he opened the door, they asked how he was doing, and he responded, “Oh, not bad for a young kid.” Seated at the kitchen table, Adele was alert and pressed the detectives to do all they could.

Tony told the detectives how he’d brought Karen pizza and biscotti on Saturday, and that Karen said she was going to have a get-together with friends. Adele pushed him to be more specific:

“Sweetheart, did she say ‘friends’ or ‘friend’?” she asked.

“I—I really can’t pin that down,” Tony replied.

Tony also mentioned a potential lead: A few hours after he dropped off the pizza, he said, he was outside and, hearing a honk, glanced up to glimpse what looked like Karen’s white car passing by. Someone was in the passenger seat. Tony had mentioned this drive-by to others that day, the exact details seeming to change each time, but all versions included the unknown passenger.

With Tony’s story in mind, officers scanned nearby houses for cameras that would have been on the path of Karen’s purported drive. They found one, but after reviewing its archive from late that afternoon for a car like Karen’s, the cops came up empty. Footage from a Ring security camera kitty-corner from Karen’s home, however, had captured images of a car in Karen’s driveway like the Toyota that Tony drove. The camera recorded only snippets of footage when triggered by movement, but the images showed the car parked at 3:12 pm, still there at 3:33, and then gone by the time the next image was taken at 3:35. The video never showed the driver.

That timeline would later become crucial. On September 19, Fitbit’s director of brand protection, Jeff Bonham, stopped by San Jose police headquarters to collect Karen’s smartwatch. He reported back to police the next day that Karen’s device had been syncing via Bluetooth every 15 minutes with its paired device. An initial analysis showed that she didn’t take any steps after 3:13 pm. The data recorded her heart rate accelerating around 3:20 pm, then taking a “precipitous drop” and ceasing altogether by 3:28. The device did not capture any more motion activity until Karen’s body was taken to the morgue. The prosecution would later allege that she was “brutally murdered in her own home while eating her last meal.” Investigators had found pieces of pizza at her feet.

On September 25, the police called Tony and asked to meet him at Karen’s house, according to Tony’s defense team. When Tony drove over, a swarm of armed police jumped from unmarked cars. One neighbor, peering out the window, heard them yell, “Put your hands up, dammit!” Tony was arrested in Karen’s driveway.

At a San Jose police station, Tony was hauled into a homicide interrogation room. “What the hell am I doing here?” he asked detectives Brian Meeker and Mike Montonye. Then he waived his right to remain silent and amiably rattled off his life history and answered questions about Karen, until one detective abruptly shifted the subject: Did Tony know what a Fitbit was? He shook his head. They told him that it was a watch with a step counter built into it. “Oh, nice,” Tony marveled, not seeing where the questioning was going. It also has a heart rate monitor, they said. “Oh, that’s better yet.”

The detectives continued: The data shows that Karen’s heart stopped at 3:28 pm, they told Tony. What’s more, they knew Tony was there at the time.

“Oh, no,” Tony said. “She was alive when I left.”

Meeker and Montonye kept Tony in the room for more than six hours, going over every aspect of the pizza visit again and again, while Tony, in his jovial manner, kept calling each of the cops “my friend.” One grew exasperated and said, “Tony, let’s get this straight. You keep calling me ‘my friend.’ We’re not friends at this point, because I’m accusing you of murder.”

At another point: “I think you caved her head in. I do. I think you did some really evil stuff.”

Tony’s response: “Not this kid. Not this kid … I’m a lovable man, family man.”

Getting nowhere, the cops started prodding at a motive. Maybe it was money? “That’s one thing we don’t need,” Tony said, with a laugh.

“Were you trying to come on to her?”

“Nev—. Oh God, yeah, right,” he said. “No way. There’s nothing … like that. I’m a happy man, a very happy man in many ways.”

Tony offered that maybe someone else was hiding in the house; he asked whether they’d found biscotti—that maybe that could lead to the culprit. “Knowing that your daughter was killed,” one detective replied, “is it reasonable to ask me about a bag of frickin’ cookies?”

“Well, they will be in evidence if somebody grab it and take it,” Tony answered.

“So the Cookie Monster did it. Is that it?”

Several times the cops left the room, but the cameras kept rolling. Alone, but aware he was still being recorded, Tony became antsy. “He looked like Jack LaLanne,” detective Brian Meeker would later tell a grand jury. “He was in there doing stretching and calisthenics and moving around, walking consistently, raising his arms above his head, stretching and twisting.” He also muttered soliloquies: “I got blamed for something I didn’t do. How did that happen? I have no idea. I didn’t do it. I didn’t do it. I did not do it … Yeah, you’re done … Screwed up. No, he’s convinced. Yep, the county jail … Lost the house. Tony Aiello in jail, wow. You’re stupid. Idiot.” During another break: “That’s my baby, my baby, my adopted daughter … Who in the hell would have done that?” Yet another break: “Never see the daylight again. I didn’t do it … Who in the hell was in the house? Hiding.”

At one point, the cops returned and told Tony that other investigators were rifling through his house at that very moment, and they’d found the same brand of knife that was in Karen’s hand at the murder scene. Tony explained he’d been a butcher. Even more concerning, the detectives went on, were the traces of blood they found on shirts in his hamper. “Is that going to be Karen’s blood?” a detective asked.

“Nope. I don’t think so.”

One of the detectives fixated on his choice of words: “That’s an interesting thing to say: ‘I don’t think so’ versus ‘Hell no.’ ” Tony offered that maybe he shook his hands when bleeding.

“Tony, there’s a crapload of stuff that you can’t explain,” the detective told him. “And if you can’t explain it, I have to use science to explain it.”

In 2009, Fitbit released its first personal tracking device. It clipped onto clothes and contained sensors to measure changes in speed and direction, using algorithms to make sense of that data. The company grew and improved its technology, releasing a model that synced with an iPhone app in 2011, then wrist-worn trackers in 2013. Today, some 27 million people use the company’s devices to see how far they’ve run or climbed, how many steps they’ve taken or hours they’ve slept or calories they’ve burned. An explosion of competitors have entered the market in the past five years, most notably the Apple Watch in 2015. That has hurt Fitbit’s business, but the number of people tracking themselves on one wearable device or another is only growing; some 170 million wearables were shipped last year worldwide.

As more people used the devices, it was inevitable that they would be worn by victims or suspects in crimes and potentially hold tantalizing clues or even plausible answers: Does a suspect’s alibi of being at home asleep hold up? Does a victim’s steady heart rate at the time of an alleged attack suggest the charge was fabricated?

Using trackers this way, of course, assumes that the devices are accurate—and not just accurate on average, but at very specific moments in time, a sort of black box for the body that reveals physiological truths that its wearer might prefer to conceal. Research on fitness trackers, however, shows they don’t always perfectly mirror reality. An analysis of 67 studies on Fitbit’s movement tracking concluded that the device worked best on able-bodied adults walking at typical speeds. Even then, the devices weren’t perfect—they got within 10 percent of the actual number of steps a person took half of the time—and became even less accurate in counting steps when someone was resting their wrist on a walker or stroller, for example. “It’s not measuring actual behavior,” says Lynne Feehan, a clinical associate professor at the University of British Columbia and the lead researcher on the paper. “It’s interpreting motion.”

Many fitness tracker users experience moments of misinterpretation: the piano playing session that was categorized as cycling; the times during sweaty exercise when it stops picking up a heart rate. Even Fitbit’s own terms of service point out that it is a consumer product with accuracy that is “not intended to match that of medical devices or scientific measurement devices.”

Smartwatches decipher heart rate using green LEDs that beam hundreds of times per second into capillaries through the skin. Those capillaries allow in more of the light when full of blood, and less between beats, and the device measures how much light is absorbed. That measurement is then siphoned through a proprietary algorithm to generate a heart rate figure. University of Wisconsin researchers looked at how well wrist-worn fitness trackers measured heart rate, comparing it to an electrocardiograph, the gold standard for heart monitoring. They found that the fitness trackers’ heart rate deviated more from the actual rate when a subject exercised on a treadmill than when at rest. (Fitbit won’t talk specifics about its accuracy, saying in a statement, “We are confident in the performance of all our devices” and that the company continues to test them.)

“Nobody has come out and said these are extremely accurate,” says Lisa Cadmus-Bertram, one of the researchers on the heart rate study. Still, such variations from real measurements don’t matter much for its typical use. “Are fitness trackers in general accurate enough that I think they provide valuable information to be useful for the typical American consumer? Yes. I think so.” With smartwatch heart trackers, “if you’re trying to determine if someone’s heart rate is exactly 80 beats versus 90 beats per minute, that’s a really hard thing,” Cadmus-Bertram says. “If you’re trying to determine if a heartbeat has ended, in my experience with these devices, they should be able to do that quite easily.”

Evidence from fitness trackers has been admitted in homicide cases in the UK and Germany. In the US, one of the first known criminal cases involving a wearable took a surprising twist because of the data it revealed. In 2015 a woman in Pennsylvania claimed that an intruder had dragged her out of bed and into a bathroom, and raped her with a bottle at knifepoint. She gave investigators permission to access her Fitbit data, which then contradicted her claim; the data showed she had been walking around all night prior to calling the police, not sleeping. “I think it’s safe to say the Fitbit evidence really sealed it for us,” says Brett Hambright of the Lancaster County District Attorney’s Office. “It presented a direct contradiction to what she claimed happened.” The woman was charged with filing a fictitious report, and she didn’t fight the charges.

So far, just a few judges have issued rulings that discuss in detail how to handle evidence from fitness trackers. In a 2016 Wisconsin case, Fitbit data was used to eliminate the possibility that a woman was murdered by her live-in boyfriend. The judge ruled that an affidavit from Fitbit established the device’s authenticity, and allowed lawyers to introduce its step-counting data; at trial, a sheriff’s department analyst vouched for the reliability of the man’s particular device. However, the judge barred the Fitbit’s sleep data, citing a class-action suit that claims the sleep tracking could be off by as much as 45 minutes. (The murder case is now being appealed.)

How other judges decide the validity of Fitbit information will likely continue to be decided in the slow burn of the legal system, and no appellate court has yet weighed in. Antigone Peyton, an intellectual property and technology law attorney who has used data from wearables in civil cases, points out that there are still no set legal standards for how and when this new type of data should be admitted. Forensic tools like bullet lead analysis and polygraph tests were once widely accepted in court, she notes, but were later dismissed as “wildly inaccurate.” People often have a sense that “data is equivalent to truth,” she says. But there are “many ways the information on these devices can be interpreted.”

Gail Gottehrer, an attorney who specializes in tech litigation and lectures at Columbia University, thinks that judges should permit jurors to weigh new types of tech evidence with guidance from expert witnesses. The thing jurors need to know, she says, is that “this isn’t like saving a Word document and printing it out. This isn’t just maintenance of data; something’s being done to this data. The algorithm is drawing conclusions.” And the jurors can decide how much weight to give the results.

Digital data has long been fair game. But now, Gottehrer says, “it’s something you’re wearing on your wrist, essentially showing the most personal information about you.” While you have the right to remain silent, your gadgets mostly do not. Still, last year, the Supreme Court ruled that people have a legitimate expectation of privacy for their phone location data, and that to protect Fourth Amendment rights against unreasonable search and seizure, police must have a warrant to search that data. While other makers of smart devices have waged high-profile fights over those orders—Amazon resisted turning over a murder suspect’s Echo recordings until the suspect himself ended the face-off by consenting—some wearable companies seem to be cooperating.

In Tony Aiello’s case, the Fitbit data came from the victim and not the accused. But police got a warrant—which is required for digital evidence under California law—for Karen’s Fitbit data.

Tony’s defense lawyers signaled that they would attack the reliability of the Fitbit data. They assembled a grab bag of disqualifications: They said Karen wore the device for only two weeks or less, and it hadn’t yet normalized to her signal; they said that Fitbit, which assigns a confidence score of 0 to 3 to its data collection, at times assigns zero confidence to the data on Karen’s device on the day the prosecution says she was murdered; and Edward Caden, one of the defense attorneys, said that what the prosecution calls a “spike” in Karen’s heart rate is more like “a pimple.” Caden even asserted that there were moments after 3:28 pm when Karen’s Fitbit seems to still report heartbeat data.

Angela Bernhard, the chief trial deputy for Santa Clara County, told me in August that she expected that the defense would “be fighting to keep out a lot of the evidence that we want in” and that she intended to present the Fitbit evidence at trial. “Ultimately it’s up to the judge what evidence gets brought in and what doesn’t,” she said. At a grand jury hearing in August, Bonham, the Fitbit executive, testified that Fitbit had turned over a voluminous Excel spreadsheet of Karen’s raw heartbeat and step data. He also clarified that a confidence rating of zero means the device isn’t registering a heartbeat at all, and detectives say that Karen’s device showed no heartbeat and zero confidence at 3:28 pm and after. Detective Meeker testified to the reliability of Karen’s device specifically: At two times in early September that Karen was visible on surveillance footage walking in stores, her Fitbit recorded movement. (Fitbit declined to comment on Aiello’s case.)

In the meantime, as the internet of things keeps expanding—porch cameras aimed out into the street to catch passing cars, cell phones tracking us pretty much always, virtual assistants listening in—criminals are going to have to become more tech-savvy or find another trade. And we all should realize there is little we can hide.

The damning timeline created by the Fitbit data, paired with the Ring footage, allowed the police to get an arrest warrant for Tony. They also got a warrant to search his home, where they seized the blood-spotted clothing in the hamper and detected blood residue in the sinks. In addition, they found a Columbia-brand camouflage jacket with blood spatter on the sleeves. They sent the items to the county crime lab for DNA testing.

Within days of Tony’s arrest, the family hired an attorney, Steven Nakano, who arranged for Tony to take a polygraph test. He passed. Nakano also latched onto another piece of evidence: a flattened cigarette that was found in Karen’s kitchen. Neither Tony nor Karen smoked. An initial DNA test showed the genetic markers of an Asian man. Victoria Robinson, the Santa Clara County prosecutor, said that the cigarette had been “placed atop one of the numerous blood spatters,” suggesting it could have been planted.

But as test results came back, the evidence started to look bad for Tony. The blood on the camouflage jacket matched Karen’s. The prosecution no longer had to rely only on the timeline woven from Fitbit and Ring data. The reliability of genetic testing, unlike data from wearables, has been established both scientifically and in criminal trials. (Even Nakano told me the blood is “hard to explain.”)

By March, after Tony had been in jail for more than five months, the family brought on a new legal team—Caden, who is a former prison warden, and a veteran defense attorney named Brian Getz. The pair recruited a retired neuropsychologist who had spent a career in California’s prison system. She interviewed Tony for 75 minutes and noted his short-term memory problems. His affability, honed during years in customer service, made him “likely to appear much more capable than he actually is,” she wrote, raising a serious question as to “how it would have been even remotely possible” for him to strategize and cover up a murder—“were it even physically possible for him to achieve this in the first place.”

As for the cigarette, Getz says that it may have been part of the “demented” fakery: “We’re not going to run from the idea that this was a staged murder scene.” But his defense intended to include an alternative theory, which Caden described to me: Karen had already been injured—cut—by someone else, and that person was in her house, hiding, when Tony arrived with the pizza and biscotti. When Tony hugged her at the door (“They hug—they’re Italians”), the blood got onto Tony’s jacket. Or perhaps it got on Tony from a tissue or Karen’s long ponytail. The prosecution declined to characterize the amount of blood found on Tony’s clothes, but Caden claims it is “not an amount of blood that would be consistent with a person who was committing the type of murder that occurred.”

The defense says it’s “very likely” the killer murdered Karen sometime after Tony left. And central to the defense’s alternative timeline would be attacking the Fitbit data that, according to the prosecution, showed Karen’s heart rate stopping at 3:28 pm on Saturday afternoon.

Bernhard, the chief trial deputy, would not discuss the case or the evidence in detail, but she called both the blood and timeline created by the Fitbit data and the Ring video “very strong evidence.”

The defense theory involves accepting some fairly bizarre circumstances—Karen being aware that a violent person was hiding in her house while she greeted Tony warmly, and Tony failing to notice, or at least to tell detectives, that Karen was bleeding. But the defense’s greatest asset might be simply the sheer cognitive dissonance of a 90-year-old man—described as a “lawn gnome” by his attorney—offering his stepdaughter a plate of pizza before allegedly bludgeoning her to death, and then apparently frustrating the detectives grilling him for hours with denials while calling them “my friend.” The fact that the prosecution hasn’t presented a motive leaves a nagging loose end. As Adele told the neuropsychologist, “That kind man wouldn’t hurt a flea.”

In his 92nd year, Tony Aiello heaved out of a hard bed each morning in the Santa Clara County jail. He no longer had his sock pullers or his velcro shoes. He took insulin shots for the diabetes he’d controlled with diet at home, and he’d been transferred to the hospital several times as his breathing and heart function worsened. Fellow inmates helped him dress, shave, and make his bed. When he spoke with his attorney in jail, he was put in leg irons, handcuffs, and waist chains fastened to an eyebolt in the concrete floor. Said Getz: “I’m terrified he’s going to die.”

In May, Tony was again wheeled into court, this time to see if he could get out on bail and await his hearings at home. That would be a rare privilege for a homicide defendant, and Santa Clara County is a tough-on-crime part of the Bay Area. The court’s evaluators recommended against release. Since his hearing in January, Tony had lost his mischievous pluck. He didn’t lift his cuffed hands to twiddle his thumbs in his family’s direction. This time he sat silently, his mouth set in a cod-like frown.

His wife and daughter sat in the gallery. The months of Tony’s incarceration seemed to have taken a toll on them too. His daughter walked with a cane. Adele was accompanied by a helper. Back at home, Tony would drive her around, buy groceries, and cook, and in his absence people had noticed she’d lost weight.

After the defense emphasized Tony’s frailty, it was the prosecution’s time to respond: “This is a murder case,” Victoria Robinson said emphatically. “This is a brutal murder case. This is a person who has gone to extreme lengths to avoid culpability—from lying to investigators to fabricating stories to throw them off to tampering with the crime scene and, very ineffectually, changing a crime scene.” She then dropped a bombshell: Two people had come to the police claiming Tony had sexually assaulted them when they were children, in the 1950s. As she spoke, the Aiellos remained stoic. Annette later brushed off the allegations as a “ploy” with “no validity.”

Judge Edward Lee, a gaunt former cop and prosecutor, told the room he didn’t need to hear more about the decades-old allegations or see crime scene evidence to make a decision. “I believe that there is clear and convincing evidence there would be a serious risk to other people in the community,” he ruled. Tony was staying in jail. When the judge asked Adele if she’d come back to testify at a later hearing, she replied, weakly, “Of course.” Later, Annette said her father had remained hopeful of getting out: “He believes justice will set him free.”

In June, Tony entered the hospital again for heart failure. This time he stayed for more than five weeks and signed a do-not-resuscitate order. At the end of August, after being indicted by the grand jury, Tony was shuttled to the hospital for the last time. A sheriff’s deputy was posted outside, and sometimes inside, the room. At points, Adele and Annette visited him as he faded, Getz said. At approximately 6:12 pm on September 10, while Annette and doctors were present, Tony died.

Having no other suspects, the prosecutor intended to dismiss the case, leaving the open matter of Tony’s guilt or innocence and the validity of smartwatch evidence to loom, unresolved for all involved. Until the end, Tony maintained his innocence, his attorneys say. Meanwhile, “We will never know what really happened to Karen,” says her old friend, Therese Lavoie. “That will bother me the rest of my life.”

Five miles from the courthouse, across from an AutoZone and another San Jose strip mall, stands a Tudor-style cottage. It’s the chapel at the entrance to Oak Hill Memorial Park, the oldest secular cemetery in California. The interred include a rider for the Pony Express and several members of the pioneering Donner Party who survived a snowbound winter in the Sierra Nevada during the push west. Past the cottage, way out into the rows of tombstones, is a coffin-sized rectangle of fresh grass, which was several shades darker than the surrounding lawn this past spring. The simple white marker, flush with the earth, reads KAREN L. NAVARRA, 1950–2018. Directly to its left stands a granite headstone inscribed with three roses and a bow. On one panel is inscribed her father’s name, Dominic Navarra, 1923–1996. The spousal panel remains blank.

Adele had been angry since Tony was arrested. She believed that the prosecutor wanted Tony to die in jail before he could clear his name. While Tony was there, Adele still answered his daily jail calls. She said she’d do anything it took to have him back at home. Before getting wheeled out of the courtroom to go back to jail in May, Tony blew Adele a mournful kiss.

***

A version of this story appears in the 27.10 issue of WIRED. After the story went to press, the transcript of a grand jury hearing in the Aiello case was made publicly available. And, on September 10, Tony Aiello died at the Santa Clara Valley Medical Center. This online version has been updated to reflect those events.