A former tenant of the founder of an African American history museum in Louisiana was charged Tuesday with her murder, authorities said.

Ronn Jermaine Bell, 38, was arrested for allegedly killing Sadie Roberts-Joseph, who was found dead in the trunk of her car on Friday, Baton Rouge police announced. He was charged with first degree murder.

A preliminary autopsy conducted by the East Baton Rouge Parish Coroner's Office showed Roberts-Joseph, 75, died of traumatic asphyxia.

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Police said they did not have a motive yet in the case, but that Bell was a tenant in one of Roberts-Joseph's rental houses and was several months behind on his rent.

Ronn Jermaine Bell Louisiana State Police

Bell was a registered sex offender who pleaded guilty in 2007 to the aggravated rape of an 8-year-old girl and served seven years in prison, East Baton Rouge District Attorney Hillar C. Moore, III, said Tuesday.

Roberts-Joseph founded the Odell S. Williams Now and Then African American History Museum, now known as the Baton Rouge African American History Museum, in 2001, according to the Advocate. The museum is part of the New St. Luke Baptist Church campus on South Boulevard, where her brother serves as pastor, the outlet reported.

The website of the city’s visitor bureau says the museum features exhibits on African art, growing cotton, black inventors and a 1953 bus from the period of civil rights boycotts in Baton Rouge, among others.

Baton Rouge Mayor-President Sharon Weston Broome said Tuesday that Baton Rouge and East Baton Rouge Parish will make Roberts-Joseph's legacy a priority "because of what she gave to so many here."

“Having knowing her for at least three decades, I can tell you as Mayor of this city, she was one of the stand out matriarchs of Baton Rouge," Broome said. "She was a part of the fabric of Baton Rouge and that is why you see so many people concerned about her death."

Roberts-Joseph's daughter Angela told reporters that she will not let her mother's work and sacrifice on educating the community about inclusivity and diversity falter in her death.

"Anyone who had ever encountered my mother knew that she was relentless," she said. "As much as I'd like to be at home right now just wallowing, I can not do that to her. She worked so hard, she pushed. She got everything that she could out of the 75 years that she lived."