Sadie Roberts-Joseph, the 75-year-old Baton Rouge African American history museum founder who was found dead in the trunk of her car last week, died from suffocation, according to the East Baton Rouge Parish Coroner's Office.

On July 15, an autopsy performed on Roberts-Joseph determined the Louisiana activist died from "traumatic asphyxia, including suffocation,” coroner Beau Clark told CNN.

Clark also revealed Roberts-Joseph was not strangled, adding her nose and mouth were both blocked. The coroner did not say whether there were any other marks or wounds on her body.

Her body was discovered at 3:45 p.m. Friday after an anonymous caller reported finding her in the trunk of her car, which was located three miles from her home, Baton Rouge police spokesman Sgt. Don Coppola told reporters.

Roberts-Joseph's family saw her earlier that day, Coppola said.

Baton Rouge Police Chief Murphy Paul said he is "confident that we're going to make an arrest" in the case as they have been investigating leads all weekend.

"The community has been working with our detectives," he told CNN's Don Lemon Monday night. "We are getting calls, we are getting emails, we are getting text messages."

"There will be no investigative lead that will not be exhausted in this investigation," Paul added.

Roberts-Joseph was known as a civil rights advocate and activist in the Baton Rouge area. She founded the Odell S. Williams Now and then African American Museum in 2001 and annually hosted Juneteenth festivities in Baton Rouge.

"Ms. Sadie was a tireless advocate of peace in the community," 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.

Roberts-Joseph also founded Community Against Drugs and Violence, a non-profit organization focused on creating a safer environment for children in north Baton Rouge. Roberts-Joseph was the organization's first president. "She's an icon. And she was our hero," her niece Pat LeDuff told CNN.

It remains unclear if Roberts-Joseph received any threats before her death. While Coppola said her death is being treated as a homicide, he said it's too early to determine whether her death is a hate crime.

The NAACP Baton Rouge Branch remembered Roberts-Joseph in a Facebook post.

"We lost a Cultural Legend Yesterday! #RIP Sadie Roberts Joseph," the group wrote. "From reviving Juneteenth, to the Culture preserved at Her Museum, she was a trendsetter and icon in this City."