Police in Louisiana are investigating the presumed slaying of a prominent civil rights activist and founder of an African-American history museum whose body was found in the trunk of her car in the state capital, Baton Rouge, officials said on Sunday.

The remains of Sadie Roberts-Joseph, 75, were discovered on Friday afternoon about 3 miles (4.8 km) from her home near the Southern University and A&M College campus, but the cause of her death was not immediately known, according to authorities.

Police were led to the victim by an anonymous caller who reported a body in the trunk of a vehicle, Baton Rouge Police Department Sergeant L'Jean Mckneely said by email.