A fatal hit-and-run investigation in Michigan has now turned into a homicide investigation, after authorities say a jogger was mysteriously shot to death while exercising.

Rebekah Bletsch, 36, was found Sunday along a quiet country road less than a mile away from her home in Dalton Township, an 8,000-population township in the western part of the state.

Despite efforts to resuscitate her, the wife and mother was pronounced dead at the scene.

The physical therapist's last contact with a family member was around 5 p.m., officials said. She was found a little over an hour later, fatally wounded, with her headphones and cellphone arm band, leaving authorities to believe she was out for a run or jog.

Investigators initially suspected a hit-and-run death. "The first witnesses that found her thought she had been hit by a car until some evidence pointed us in the other direction," Muskegon County Sheriff Dean Roesler said.

Investigators say the evidence included shell casings near Bletsch's body, as well as a small bullet wound.

The wife and mother had been shot in the head.

Now, Michigan State Police are forming a task force with the Sheriff's Office to investigate the death, Dalton Township's first homicide of the year.

Relatives are devastated by Bletsch's death. "There's no scenario that makes sense, can bring any kind of understanding to what transpired," Tim Donkin, her husband's uncle, said.

Bletsch was found with several valuables, making robbery an unlikely motive.

Her husband and 11-year-old daughter were out of town during the time of the shooting, and investigators say her husband is not a suspect.

Donkin described Bletsch as vibrant, the kind of person who would always bring a smile to people's faces.

"She was always willing to pitch in and help, always seemed to be concerned about others," he said. "Becky was not just a person running down the road – she had a life."

Police are now checking Bletsch's cellphone records to uncover whether she was in contact with anyone before the shooting.

Bletsch's autopsy results, which are expected back today, could also provide clues.