Man accused of beating girlfriend to death before astonishing Fitbit discovery

The partner of a woman who was brutally beaten and murdered was able to prove his innocence, thanks to his Fitbit device.

Nicole Vander Heyden was out with friends on the evening of May 20, 2016, but never returned home. At the time of her disappearance, Nicole had been living with her boyfriend, Doug Detrie, and their six-month-old son.

At around 4pm the next day, Doug called the police and reported Nicole as missing. But tragically, days later, Nicole's lifeless body was found in a field three miles from their home in Wisconsin, US.

It was reported that she had been beaten and strangled to death, with 241 separate injuries inflicted on her. An investigation into her death was launched, while her family and friends were left devastated over the loss of Nicole.

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Her partner, Doug, swiftly became a prime suspect after concerns were raised about the length of time it took for him to raise the alarm about her whereabouts to the police. In addition, he had allegedly taken a shower before arriving at the station to give a statement.

"It doesn't seem like a guy who's particularly worried about his girlfriend, the mother of his child, does it?" Slinger told '48 Hours' correspondent Erin Moriarty.

Doug was arrested, but his name was later cleared, thanks to his Fitbit device. During the time frame that Nicole's murder took place, Doug's Fitbit readings were said to reveal "minimal activity".

The prosecution successfully argued that this recorded Fitbit data did not align with the brutal murder that took place, which saw Nicole fatally beaten. He had also been wearing his Fitbit device during his police interview.

In addition, there had been no physical evidence linking Doug to the horrific crime.

Then, DNA from a man called George Burch was found on the electrical cable that was used to strangle Nicole. Burch was charged with the murder of Nicole and sentenced to life in prison without parole.

"Nobody knew who he was," Kate Briquelet, a writer for the Daily Beast, told CBS News. "He had no connection to Nikki, no connection to Doug, no connection to any of their friends. I mean, he was literally a mystery man."

According to reports, Burch met Nicole at the bar on the night she had been out and offered her a lift home before committing the horrifying crime.