iStock(BATON ROUGE, La.) — A Louisiana man has been arrested in the murder of a beloved 75-year-old community activist whose body was discovered asphyxiated in the trunk of her car, police said at a news conference Tuesday afternoon.The death of Sadie Roberts-Joseph, who founded an African American museum in Baton Rouge and teamed up with police on an anti-drug and violence program, was ruled a homicide by “traumatic asphyxia, including suffocation,” according to an autopsy report.Ronn Jermaine Bell, 37, a convicted sex offender, was taken into custody Tuesday on a charge of first-degree murder, police said.Bell was living in one of the homes Roberts-Joseph was renting out and it is believed he was several months behind in rent payments, police said. Authorities estimated Bell owed Roberts-Joseph $1,200.“On behalf of the family of Sadie Roberts-Joseph we would like to express our sincere appreciation to all of the entities that came together in this tragedy to bring this person to justice,” Roberts-Joseph’s daughter, Angela Machen, said during Tuesday’s news conference.Police said numerous leads came in from community residents and helped police identify and arrest Bell in the slaying.“All my mother ever wanted was for this community to come together. It’s ironic that that happened in her death,” Machen said.Roberts-Joseph was found slain Friday afternoon when police were directed by an anonymous 911 caller to her car parked behind a vacant house northeast of downtown Baton Rouge, said the city’s police Chief Murphy Paul.“Our detectives immediately began following up on leads, interviewing witnesses and searching for evidence during the midst of a hurricane,” Paul said at Tuesday’s news conference. “We say we can’t do this without the community and this is an example of when a community steps up and does their part we’re able to put these bad actors away.”During an interview with homicide detectives, Bell denied seeing Josephs-Roberts on the day she was killed, according to an arrest warrant affidavit.But detectives obtained surveillance video that showed Bell “in the same exact area the victim’s vehicle was abandoned at the same exact time the vehicle was abandoned,” according to the affidavit.Bell matched the description from a witness of a man seen abandoning the vehicle and walking away, the affidavit reads.The suspect’s DNA was also found on the victim’s body, according the affidavit.Roberts-Joseph was last seen alive visiting her sister about 11 a.m. on Friday. Her body was discovered in her car a little over three miles from her home about 3:45 p.m. on Friday, police and relatives said.There was a 90 minute time frame that investigators focused on, from the time she was last seen alive to the time her body was found, police said.A warrant was already issued for Bell on unrelated charges, including failing to comply with probation regulations and failing to register as a sex offender.Bell was previously convicted for sexual assault against an 8-year-old girl, said East Baton Rouge District Attorney Hillar C. Moore III, adding that Bell pleaded guilty in 2007 to sexual battery and received a seven year sentence, which was completely served.The slaying of Roberts-Joseph, who was well known in Baton Rouge, came as a complete shock for her family and the community.“We’re devastated that someone has actually killed her and put her in the trunk of her own car,” Roberts-Joseph’s niece, Pat McCallister-Leduff, told ABC News.The victim’s sister, Beatrice Johnson, told The Advocate newspaper of Baton Rouge that Roberts-Johnson stopped by her house around 11 a.m. on Friday. She said her sister lived near her in the Scotlandville neighborhood of Baton Rouge and would check in with her daily.“Friday, she came by [because] she had mixed some cornbread, but her oven went out, and she brought it here to put in the oven,” Johnson told the newspaper. “The bread is still there. She never came back to get it.”Roberts-Joseph founded the Odell S. Williams Now and Then African-American History Museum in 2001. The museum, now known as the Baton Rouge African-American History Museum, is housed on the campus of New St. Luke Baptist Church in Baton Rouge.She also organized the city’s annual Juneteenth festival at the museum, commemorating the day slaves were belatedly freed in Texas more than two years after Emancipation Proclamation was signed. She also partnered with Baton Rouge police to launch a Community Against Drugs and Violence program.In a recent interview with ABC affiliate station WBRZ in Baton Rouge, Roberts-Joseph said her work at the museum and the annual Juneteenth event was meant “to celebrate, to embrace” African American history and to “learn of our past and to be able to move forward in unity.”Baton Rouge Mayor Sharon Weston Broome described Roberts-Joseph on Tuesday as “one of the standout matriarchs of Baton Rouge.”“She was a part of the fabric of Baton Rouge and that is why you see so many people concerned about her death,” the mayor said. “We will make her legacy a priority here in Baton Rouge … because of what she gave to so many here.”East Baton Rouge Sheriff Sid Gautreaux said he personally knew Roberts-Joseph.“I’m heartbroken that our community has lost such a kind and selfless soul in such a violent, tragic manner,” Gautreaux said. “I’ve known and loved Ms. Sadie for years and admired and respected her dedication to education and our community. I’m grateful for the swift action of the Baton Rouge Police Department and the Louisiana State Police in finding her alleged killer and putting him behind bars.”Copyright © 2019, ABC Radio. All rights reserved.