A 90-year-old man has been arrested for allegedly killing his stepdaughter after investigators gained information from the Fitbit she wore at the time of the incident, according to police. 
 
 When authorities responded to a welfare check Sept. 13 at the San Jose home of 67-year-old Karen Navarra, they found her dead at the scene, the San Jose Police Department said. 
 
 She had a gaping laceration on her neck, a deep laceration on her head and a kitchen knife in her hand, according to the statement of facts written by police and provided by the Santa Clara District Attorney's Office. 
 
 A medical examiner determined Navarra couldn't have caused all the wounds herself and detectives believed the scene was staged to appear as a suicide, the document said. 
 
 Police spoke to Navarra's stepfather, 90-year-old Anthony Aiello, who is married to Navarra's 92-year-old mother. 
 
 Aiello told police he last saw Navarra Sept. 8 when he brought pizza and biscotti to her at home; Aiello said he stayed there for about 15 minutes then drove home, the document said. 
 
 San Jose Police Department 
 
 Aiello told police when he was later outside his house, he heard a car honk and saw Navarra drive by waving with a second person in the passenger seat, the document said. Police recovered surveillance video from near Aiello's home and determined Navarra never drove by that day, the document said. 
 
 Navarra had a Fitbit Alta HR on her left wrist when she was found, according to police. 
 
 The data showed a significant spike in her heart rate Sept. 8 at 3:20 p.m., followed by a rapid slowing, the document said. The Fitbit stopped registering heart rate data that day at 3:28 p.m. 
 
 “ ” He denied that he was present when she was killed and suggested that someone else might have been in the house. 
 
 Police also checked surveillance video near Navarra's home and determined Aiello's car was parked in his stepdaughter's driveway from 3:12 p.m. to at least 3:33 p.m. on Sept. 8, the document said. 
 
 Aiello, of San Jose, was arrested and charged with murder Sept. 25, police said. 
 
 Aiello was read his Miranda rights and interviewed by police, during which he confirmed he was at his stepdaughter's home at about 3 p.m., the document said. Aiello told police he dropped off the pizza, didn't see anyone else in the home and left after five to seven minutes, the document said. 
 
 Aiello said his stepdaughter walked him to the door and handed him two roses when he left, the document said. 
 
 "During the interview, Aiello was confronted about the information from Fitbit and the corresponding surveillance video indicating that his car was in the driveway,” the document said. “After explaining the abilities of the Fitbit to record time, physical movement and heart rate data," investigators told Aiello his stepdaughter had died before he left. 
 
 But Aiello "denied that he was present when she was killed and suggested that someone else might have been in the house," the document said. 
 
 During the interview, investigators also told the 90-year-old man that police found two shirts with blood splatter in his garage; he responded that he cuts himself frequently, the document said. 
 
 "He was told that the deposits of blood were not localized in one area and were more consistent with splatter," the document said. "Aiello indicated that he might have cut his hand and shaken it while he was wearing those shirts." 
 
 Aiello appeared in court last Thursday before being remanded to custody, with no bail, authorities said, adding that he is scheduled to return to court this Thursday for plea proceedings and identification of counsel. 
 
 A representative for Fitbit declined to comment to ABC News on the case. 
 
 This isn't the first time a Fitbit was used as evidence to make a murder arrest. 
 
 Richard Dabate is accused of killing his wife in Connecticut in 2015; a piece of evidence against Dabate is that the victim's Fitbit data contradicted what he told police, according to the Hartford Courant. He has pleaded not guilty and is awaiting trial. 
 
 Also, when Iowa jogger Mollie Tibbetts vanished this summer, investigators said they were looking into what information could be gathered from her Fitbit. The data was not ultimately used in making an arrest in her killing. 
 
 This report was featured in the Tuesday, Oct. 2, 2018, episode of ABC News' daily news podcast, "Start Here." 
 
 "Start Here" is the flagship daily news podcast from ABC News -- a straightforward look at the day's top stories in 20 minutes. Listen for free every weekday on Apple Podcasts, Google Podcasts, iHeartRadio, Spotify, Stitcher, TuneIn, or the ABC News app. On Amazon Echo, ask Alexa to "Play 'Start Here'" or add the "Start Here" skill to your Flash Briefing. Follow @StartHereABC on Twitter, Facebook and Instagram for exclusive content, show updates and more. ||||| A woman’s Fitbit clocked a rapid rise in her heart rate before a sudden drop-off to nothing, helping San Jose police piece together clues and charge her 90-year-old stepfather with her murder, according to court records. 
 
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 Tony Aiello was arrested Wednesday on suspicion of murdering his 67-year-old stepdaughter, Karen Navarra, on Sept. 8. Aiello is married to Navarra’s 92-year-old mother. 
 
 
 
 Navarra, a pharmacy technician described by family as a “recluse,” was discovered deceased by a co-worker Sept. 13 after she failed to show up to her job. 
 
 Police said Navarra was found slumped over in a chair, clutching a large kitchen knife with a “gaping” slit to her neck. To investigators, the scene appeared to be staged to look like a suicide. 
 
 But a later autopsy revealed “multiple deep and intrusive wounds” to her head and facial area, most likely inflicted by a small hatchet or ax. The doctor told investigators Navarra couldn’t have inflicted the wounds herself and classified the case as a homicide. 
 
 At his initial interview, Aiello told San Jose police that he dropped by Navarra’s home on Saturday, Sept. 8, to bring her pizza, according to court records. He also said he was outside his own home a few hours later, and witnessed his step-daughter drive by and honk with someone else in the passenger seat. 
 
 But police say Aiello’s account didn’t match up with what they saw on surveillance footage. 
 
 Nearby cameras captured his car at Navarra’s home for at least 21 minutes that day, between 3:12 p.m. and 3:33 p.m, but they didn’t show her car ever leaving in the direction Aiello described, police said. 
 
 Investigators noted Navarra was wearing a Fitbit, a wristband device that can collect data like number of steps walked and heart rate, when she was found, and they later consulted with the company to see if the device could offer any clues. A company employee told police Navarra’s heart rate spiked at 3:20 p.m. Sept. 8 and then rapidly slowed. The device stopped registering a heartbeat at 3:28 p.m. 
 
 Aiello repeated his initial story after his arrest and denied that he killed his stepdaughter, according to court records. When confronted with the Fitbit evidence Aiello suggested someone else could have been in the home. He told police she couldn’t have died when he was there, because she walked him to the door. 
 
 Police also found clothes in his hamper covered in blood splatter. Aiello told police he cuts himself frequently, according to court records. 
 
 Homicide investigators across the country have turned to fitness trackers to help piece together timelines, movements and other key information for their cases. 
 
 A Connecticut man was arrested after his wife’s Fitbit data showed her last movements were more than an hour after her husband said she had been killed by intruders. 
 
 In Wisconsin, another man’s Fitbit acted as an alibi. The device corroborated his story during a crucial window of time when police said his live-in girlfriend’s body was being dumped in a field. 
 
 Aiello is being held without bail and is due in court Oct. 4. 
 
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– Police in San Jose believe a 90-year-old man murdered his 67-year-old stepdaughter—and he might have gotten away with it if she hadn't been wearing a Fitbit. Police say they found Karen Navarra dead at her home Sept. 13 with a kitchen knife in her hand and deep wounds to her head and neck, ABC News reports. After the medical examiner concluded that she had been murdered by somebody who tried to make the death look like a suicide, investigators used surveillance footage to determine that stepfather Anthony Aiello had visited her the day of her death. He told them he had seen her later in the day—but her Fitbit revealed that her heart rate spiked, slowed, then stopped while he was at the house. During a police interview, "Aiello was confronted about the information from Fitbit and the corresponding surveillance video indicating that his car was in the driveway," police said in a statement. After police explained "the abilities of the Fitbit to record time, physical movement and heart rate data," Aiello claimed somebody else must have been in the house. He also claimed that two shirts with blood splatter found in his garage must have gotten that way after he cut himself and shook his hand, KOAT reports. Aiello, who is married to Navarra's 92-year-old mother, was arrested and charged with murder last week. (A Fitbit told a different story after this man said a fat intruder killed his wife.)