Police are investigating Roberts-Joseph's death as the community mourns.
"We lost a Cultural Legend Yesterday," the NAACP Baton Rouge Branch said in a Facebook post. "From reviving Juneteenth, to the Culture preserved at Her Museum, she was a trendsetter and icon in this City".
Rep. C. Denise Marcelle reflected on the loss in a Saturday morning Facebook post.
"My heart is empty... as I learned last night that Ms. Sadie Roberts Joseph was found murdered! This woman was amazing and loved her history," she wrote. "She never bothered anyone, just wanted to expand her African American Museum downtown, where she continually hosted the Juneteenth Celebration yearly. I loved working with her and am saddened by her death.... whoever knows what happened to her, please contact the authorities and say something. RIP my friend!!!"
"We ask that anyone who has information related to this case please call our detectives at 225-389-4869 or Crime Stoppers at 225-344-STOP (7867)," the department said.