Who killed Nicole Brown Simpson and Ron Goldman?

O.J. Simpson will serve the remainder of his prison time in protected custody. Officials changed his status for safety reasons after a parole board voted unanimously last week to approve his release.

Simpson could walk out as soon as October 1, after serving nine years for armed robbery in Nevada.

In 1995, he was acquitted of the murders of his ex-wife, Nicole Brown Simpson, and her friend, Ron Goldman. 

CBS News correspondent Jericka Duncan reports the case is still an open investigation for the Los Angeles Police Department. 

A reported 13.5 million people tuned into Simpson's parole hearing last week. That's far fewer than the estimated 150 million people who watched his 1995 acquittal. 

Still, it shows the O.J. obsession lives on, as well as the debate over who killed Nicole Brown and Goldman. 

"I'd just like to get back to my family and friends and believe it or not, I do have some real friends," Simpson said in court last week. 

It's unclear what life outside prison will look like for Simpson. But one thing is certain — it'll be a world well acquainted with his past. 

"People will always want to be a part of the O.J. case," Loyola Law School professor Laurie Levinson said. "They'll always be looking for evidence that the LAPD missed. That's because it's a mystery that to some has not been solved." 

A string of TV films this past year reignited America's fascination with Simpson's acquittal.

"The word 'open' for an investigation can mean so many things," Levinson said. "It may simply mean that because O.J. was acquitted, and they've never found another murderer, there's no reason to shut it down." 

Immediately following the 1995 verdict, Simpson vowed to find justice for his ex-wife in a statement read by his son, Jason: "I will pursue as my primary goal in life, the killer or killer who slaughtered Nicole and Mr. Goldman."

But no additional arrests were made. Simpson went on to release what was called a fictional account of the crime entitled, "If I did it." That book caused former Simpson trial juror Lionel Cryer to have a change of heart. 

"The book was the turning point for me to go to the feeling that he probably did kill those people," Cryer said. 

Simpson has repeatedly maintained his innocence. Last year, there appeared to be a possible break in the case when a knife was reportedly discovered on the property Simpson once owned. But the tip led nowhere, leaving the case largely where it was in the 1990s. 

"O.J. cannot be tried again because of double jeopardy, but he certainly can be questioned," Levinson said. "In fact, he doesn't have Fifth Amendment protection anymore."

The LAPD wouldn't provide any additional details in the case. Legal experts say there are plenty of challenges that go with investigating a crime that is more than 20 years old. Among them, the fact that prosecutors are dealing with decades-old evidence and memories.