O.J. Simpson has been a hot topic this year, and it doesn't look like that's going to end anytime soon.

After ESPN's seven-hour-and-43-minute documentary on Simpson concludes on Saturday, you'll be able to see more of Simpson in a separate documentary produced by Reelz.

The Reelz documentary, which is called Kardashian: The Man Who Saved O.J. revolves around Robert Kardashian. It aired on June 13 and re-raised some questions about the paternity of Khloe Kardashian.

In the documentary, a guard who used to watch over Simpson at the Lovelock Correctional Center in Nevada is interviewed and shares some interesting tidbits.

The guard, Jeffrey Felix, was in charge of watching Simpson for several years and even wrote a book called Guarding the Juice.

According to Felix, Khloe Kardashian once begged Simpson to take a paternity test because she wanted to find out if he's her father. In a further interview with the Daily Mail, Felix explained that Simpson would be willing to take a paternity test, but only on one condition: She has to visit him in prison.

O.J. Simpson has resurfaced in the news this week. Getty Images

"She has to go there and talk to him. He wants her to come out to Lovelock and visit him in person," Felix said. "O.J. will do it and the prison officials have told him they will allow it. It's just a quick mouth swab and they would allow it to happen during a visit."

Simpson could obviously submit to the test without Khloe being present, but Felix says that's not going to happen.

"He wants to talk to her about some other things, too, but more importantly like her he wants to know if she is his daughter," Felix said.

Simpson has been behind bars at Lovelock since October 2008 when he was convicted of armed robbery and kidnapping in Nevada.

As for Khloe, the question of who her father is has lingered for several years. In a 2009 episode of Keeping up with the Kardashians, Khloe has her mom, Kris Jenner, take a DNA test because doesn't think she looks like her brother (Rob) or two sisters (Kim, Kourtney). Of course, there was no paternal DNA test, so Khloe didn't get to the bottom of the mystery.

The identity of Khloe Kardashian's father remains a mystery. USATSI

Part of the mystery also revolves around Khloe's mom, who admitted in a 2011 memoir that she cheated on Robert while the two were married.

The mystery was revived in 2012 when two of Robert Kardashian's ex-wives did an interview with Star Magazine, where both said the same thing: Robert wasn't Khloe's father.

Robert passed away in 2003.

Jan Ashley was Robert's first wife after he divorced Kris Jenner, and she was emphatic that Khloe wasn't actually a Kardashian.

"He just kind of looked at me and said (it) like it was a matter of fact," Ashley said in 2012. "He said, 'Well, you know that Khloe's not really a Kardashian, don't you?' And I said ... 'Okay,' and that was it."

Another ex-wife, Ellen Kardashian, noted that it was a common thing for Khloe to talk about while she was growing up.

"Khloe brought it up all the time," Ellen Kardashian said in 2012. "She looked nothing like the rest. She was tall, had a different shape, light hair, curly hair. Didn't look anything like the other three children."

After the two interviews came out, Khloe wasn't a happy camper.

Robert Kardashian was a long-time friend of Simpson. The Kardashian family patriarch was a member of Simpson's "Dream Team" that successfully defended him after he was charged with two counts of murder following the deaths of Ronald Goldman and his ex-wife Nicole Brown Simpson.

This marks the second time this week that a Kardashian family member has made headlines for something related to Simpson. Earlier this week, Kim did an interview with GQ, where she claims to have solved the mystery of a garment bag that went missing from Simpson's estate the day after the murders were committed in June 1994.