Nicole Brown Simpson's three sisters have branded OJ Simpson an "abuser"

Referring to how Nicole called police multiple times to report Simpson for abuse, Denise told the Variety Power of Women at the Cooper Hewitt, Smithsonian Design Museum in New York City: "We lost Nicole almost 30 years ago.

"Nicole endured incredible pain and through that pain she was able to protect her children.

"She walked away from her abuser. She was a daughter, she was a sister, she was a mother, she was a friend, she was a woman whose life was tragically cut short."

Denise also discussed the Violence Against Women Act, which she helped get passed, in front of A-list guests at the event, including Glenn Close, Nicky Hilton, Tamron Hall, and Melissa Joan Hart.

Nicole's sisters have spent years paying tribute to Nicole by helping female domestic violence victims and will appear in a new Lifetime documentary called 'The Life and Murder of Nicole Brown Simpson' in June.

Denise told Variety about the project: "I have wanted to do a documentary for 10 years, but I never felt the timing was right.

"I thought if I could find someone who would make Nicole's voice be heard, and not make it about the trial or him, I would be happy.

"It was extremely sad when people would tell me, 'We don't even know what her voice sounds like.'

"It broke my heart because nobody gave her that opportunity."

Nicole was married to Simpson from 1985 to 1992, and her murder has been back in headlines in the wake of Simpson's death in Las Vegas aged 76 in April from metastatic prostate cancer last month.

Simpson was arrested once, in 1989, after Nicole repeatedly reported him for alleged abuses, and he pleaded no contest to spousal abuse.

Nicole dropped the charges after her parents encouraged her to reconcile with the sports star.