State Police have identified the man as 34-year-old Gyrth Rutan of Sturbridge, Massachusetts.
Authorities say an autopsy shows Rutan died of a shotgun wound to the head and his death has been ruled a suicide.
State Police also found the body of a woman in the trunk of the vehicle Rutan was driving. State Police say that death did not take place in Maine.
Now, both the Worcester County District Attorney's Office in Massachusetts and Maine State Police are investigating the woman's death there.
According to police, it is unclear why Rutan drove to Maine.
Authorities say he has family located in Maine and a social media page shows he grew up in Brewer.
The investigation began after troopers pulled over Rutan's car after receiving reports it was driving erratically on Interstate 295.
A trooper spotted the car on the Interstate and then followed it along Route 201 until it turned onto Timberwood Drive where the car stopped.