He said he was asleep at time of wife's murder. His health app said otherwise.

While not necessarily impartial, your smartphone is one hell of an observer.

An Alabama man found that out the hard way this week when he was sentenced on Monday to 16 years in prison for killing his wife. While there were numerous factors leading to Jeff West's conviction in November on charges of reckless manslaughter, AL.com, an Alabama news site, reports that data from his smartphone's health app played a role.

West reportedly told law enforcement that he had gone to sleep around 10:30 p.m. the night of his wife's death in 2018. However, according to data from his phone's health app, he took 18 steps between 11:03 p.m. and 11:10 p.m.

His deceased wife, Kat West, was 42 year old.

This is not the first time that data from a health tracker has been cited in a murder case. In the case of a 2016 death, police relied on the victim's Apple Watch data to disprove the claims of her accused killer. In 2017, Fitbit data contradicted a man's story about the death of his wife. Apple heath-app data was also used as evidence following a 2016 murder in Germany.

Notably, it was not just Jeff West's phone data that appeared to contradict his claims. AL.com reports that Dr. Stephen Boudreau, an Alabama Department of Forensic Sciences pathologist who testified at the trial, found that the blow to Kat West's head was likely not caused by a fall. Instead, he noted that whatever delivered the blow "had an edge, but it wasn't sharp."

An absinthe bottle was found near Kat West's body.

The tragic killing of Kat West, and the subsequent conviction of Jeff West, serves as a reminder that our technology is constantly running in the background — a fact that police are not soon to forget.

While this might have brought justice in the case of Kat West, it is easy to envision similar data being used in an altogether different manner. A Gainesville, Florida man, Zachary McCoy, was investigated for burglary simply because his phone location data put him near the scene of a crime. (He was on an innocent bike ride.)

SEE ALSO: Activists demand Google open up about user data shared with police

“I didn't realize that by having location services on that Google was also keeping a log of where I was going," McCoy told NBC News. "I'm sure it's in their terms of service but I never read through those walls of text, and I don't think most people do either."

Law enforcement, however, is undoubtedly familiar with those terms of service — something to remember the next time you head to a peaceful protest.