(Reuters) - A former tenant of a Baton Rouge civil rights activist has been arrested and charged with her murder, police in the Louisiana capital said on Tuesday.

Baton Rouge detectives arrested Ron Jermaine Bell in the killing of Sadie Roberts-Joseph, 75, whose body was found stuffed in the trunk of her car on Friday afternoon, Police Chief Murphy Paul told a news conference.

Bell was one of Roberts-Joseph’s tenants and was behind on about $1,200 in rent, Paul said. The suspect was already in jail in East Baton Rouge Parish for failing to register as a sex offender when police linked him to the murder, said Sheriff Sid J. Gautreaux, III, at the same news conference.

Roberts-Joseph’s death was ruled a homicide by the East Baton Rouge Parish Coroner’s Office on Monday. A preliminary summary of the autopsy found that her death was caused by “traumatic asphyxia, including suffocation.”

Police said they were still investigating the motive for the killing but have ruled out the possibility of a hate crime. It had nothing to do with her activism, authorities said.

Roberts-Joseph was known for founding the Baton Rouge African-American History Museum and launching the non-profit group Community Against Drugs and Violence.