The deaths of Gary and Laura Johnson will be listed as homicides, authorities said Monday.
Their bodies were unearthed Friday at Gourdneck State Game Area in Portage, about three miles from their home.
Police entered the home last Tuesday and found signs of violence after Gary’s employer said he had not logged on for work, Portage Public Safety Director Nick Armold said last week.
The couple’s 27-year-old son is in custody on other charges. Police said he was found in a storage unit at an apartment building and had his parents’ car.
Laura Johnson, 65, got a personal protection order against their estranged son in 2018, saying he needed mental health care. She said he assaulted them, damaged property, and refused to leave their home, WWMT-TV reported.
Portage is about 57 miles (91 kilometers) south of Grand Rapids.