The body of 39-year-old Edward A. Brooks was found on the property of West Rock State Park on Wintergreen Avenue at around 11:15 a.m.
Police said Brooks lived at 59 Front Ave. in West Haven.
On Monday, police said they had arrested Christopher Miller, 40, James Bryant, 64, Natali Martinez-Sanchez, 29, and Deborah Miller, 59.
According to the chief medical examiner, Brooks died of multiple gun shots trauma to head, neck and torso. His death was ruled a homicide. According to police, there was also an explosion in the same area, which harmed the body.
Christopher Miller, a convicted felon, was charged with the murder of Brooks, who was also his roommate. Police said Brooks was shot in his home in West Haven and then taken to a rural area in Hamden where he was blown up with an explosive device.
Neighbors in the area of the explosion said it is a calm neighborhood to live in.
"Its got to be one of the calmest neighbors you ever want to live in. Just great people," said Pat Palmieri, adding that the explosion shook the house.