The founder of Baton Rouge’s African American history museum who was slain in the city last week died of suffocation, and her death has been ruled a homicide, the city coroner’s office determined Monday.

Sadie Roberts-Joseph, 75, who was also a community activist who teamed up with local police in anti-violence initiatives, was found dead in the trunk of a car about 3 miles from her home in the city on Friday, police said.

East Baton Rouge Coroner Beau Clark said on Monday that she died of “traumatic asphyxia, including suffocation,” meaning her airway was physically blocked until she died.

Roberts-Joseph founded the Baton Rouge African American Museum in 2001 and was its curator. The museum features a bus that visitors can climb onto to learn about the 1953 bus boycott in the city.

She also organized an annual Juneteenth festival at the museum, marking the date June 19, 1865, when announcement of the abolition of slavery in the US state of Texas was made.

“Ms. Sadie was a tireless advocate of peace,” the Baton Rouge Police Department said in a statement. “Our detectives are working diligently to bring the person or persons responsible for this heinous act to justice.”

With Post wires