Her stepfather, Anthony Aiello, told police he had visited Navarra on Sept. 8, bringing her pizza and biscotti and staying for about 15 minutes. But security footage showed the 90-year-old man’s car was still in the driveway when her heart rate spiked, slowed, then stopped, which police determined with data from the Fitbit Alta HR activity tracker that Navarra was wearing when she died.

Aiello, who is married to Navarra’s 92-year-old mother, was arrested last week on murder charges and booked into the Santa Clara County Jail, the New York Times reports. He’ll appear in court in San Jose today.

It’s not the first time Fitbit (FIT) records have been used in a murder investigation. Connie Dabate was killed in her Connecticut home in December 2015, and with the help of her fitness tracker’s records and Facebook postings, police implicated her husband, Richard Dabate, who is now charged with murder. Iowa police also scoured Fitbit records in the Mollie Tibbetts investigation this summer.

Fitbit’s cooperative attitude with law enforcement contrasts with that of Apple, which declined to provide the FBI with a software backdoor to break into the iPhone Syed Rizwan Farook, one of the shooters in the 2015 San Bernardino mass killing.

Fitbit was not immediately available to comment. Fitbit’s privacy policy states: “We may preserve or disclose information about you to comply with a law, regulation, legal process, or governmental request; to assert legal rights or defend against legal claims; or to prevent, detect, or investigate illegal activity, fraud, abuse, violations of our terms, or threats to the security of the Services or the physical safety of any person.”

The Alta HR was released in spring 2017, adding heart rate tracking to the previous year’s Alta model. Fitbit’s attempts to enter the smartwatch market have been moderately successful, holding about one-fifth of the U.S. smartwatch market in the second quarter of this year.