The founder of an African American history museum in Louisiana was found dead in the trunk of a car on Friday afternoon, police said. The cause of death for Sadie Roberts-Joseph, who was considered an icon in the Baton Rouge community, has not been determined, but two local officials said she was murdered.

Police found the body of Roberts-Joseph, 75, in a car about 3.5 miles from her home, CBS Baton Rouge affiliate WAFB reports. Authorities have not said what led to her body being discovered.

In 2001, Roberts-Joseph founded the Odell S. Williams Now & Then Museum of African-American History, which is now known as the Baton Rouge African-American History Museum. She was revered in Baton Rouge for her charity and activism and for helping to start the annual Juneteenth celebrations in Louisiana's capital city commemorating the ending of slavery.

Get Breaking News Delivered to Your Inbox

"Ms. Sadie was a tireless advocate of peace in the community. We had opportunities to work with her on so many levels," the Baton Rouge Police Department said in a statement.

"Ms. Sadie is a treasure to our community. She will be missed by BRPD and her loss will be felt in the community she served."

The department added, "Our detectives are working diligently to bring the person or persons responsible for this heinous act to justice."

Baton Rouge Mayor Sharon Weston Broome and state Rep. C. Denise Marcelle both said Roberts-Joseph was murdered — something police have not confirmed. CBS News could not immediately reach representatives for the police department.

"In the midst of managing a major weather event in our parish, I was hit with some devastating news — the murder of a dear friend and a mother of the community — Sadie Roberts-Joseph," Broome wrote in an Instagram tribute posted Sunday. "I've deliberately waited to comment because of the level of love and respect I had for Sadie; and because it was such shocking news. She loved this city and its people. Her commitment to the cultural and educational fabric of our community is beyond description."

Marcelle said Roberts-Joseph "never bothered anyone" and wanted to expand the museum she founded.

The NAACP branch in Baton Rouge called Roberts-Joseph a "Cultural Legend."

"From reviving Juneteenth, to the Culture preserved at Her Museum, she was a trendsetter and icon in this City," the group said.

No suspects have been named in connection with Roberts-Joseph's death. An autopsy will be conducted to determine the cause of her death.