https://www.nytimes.com/2018/10/03/us/fitbit-murder-arrest.html

«She had been wearing a Fitbit fitness tracker, which investigators said showed that her heart rate had spiked significantly around 3:20 p.m. on Sept. 8, when Mr. Aiello was there.

Then it recorded her heart rate slowing rapidly, and stopping at 3:28 p.m., about five minutes before Mr. Aiello left the house, the report said.»