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OMAHA, NEB. (CBSNews.com)- Tommy Morrison, the former heavyweight champion who stood toe-to-toe with Lennox Lewis and George Foreman and later tested positive for HIV, died Monday. He was 44.

Morrison died Sunday night at a Nebraska hospital, said Tony Holden, his longtime promoter and close friend. The family would not disclose the cause of death.

In 1993, Morrison beat Foreman to win the WBO heavyweight title, only to lose it to unheralded Michael Bentt in a defeat that scuttled a showdown with Lewis. Morrison would fight Lewis a couple of years later, getting knocked out in the sixth round in Atlantic City, N.J.

Morrison, nicknamed "The Duke," never reached the status of such contemporaries as Mike Tyson and Evander Holyfield, but it was surely a full career.

He was a prodigious puncher whose bid to fight in the 1988 Seoul Olympics ended at the hands of Ray Mercer, who later dealt Morrison his first professional loss. He had a starring role in "Rocky V" alongside Sylvester Stallone. And perhaps most memorably, Morrison tested positive for HIV when the virus still carried a significant stigma, only to declare later the test was false.

Along with numerous legal issues, including a prison sentence that stemmed from weapons and drunk driving, Morrison's name became attached to headlines that would eventually overshadow his work in the ring.

"If Tommy was fighting today, he no doubt would be a world champion," Holden said. "You have to look at who he was fighting in the `90s, the guys in that division were Tyson, Lennox Lewis, Riddick Bowe, Ray Mercer, George Foreman. There's no one with that talent today. Tommy would absolutely dominate if he were in his prime boxing today."

Morrison won his first 28 professional fights, beating faded champions such as Pinklon Thomas along the way. His career reached its apex in the summer of 1993 with a unanimous decision over Foreman, then in the midst of his comeback, to claim a vacant title.

As with so many things in Morrison's life, the good was quickly followed by the bad.

Morrison was in line for a high-profile bout with Lewis when he was upset by Bentt in Tulsa, Okla., not far from where Morrison was raised. He was knocked down three times and the fight was called before the first round ended.

Along with the stinging defeat, Morrison saw a potential $7.5 million payday for a title unification fight against Lewis wash away.

"I zigged when I should have zagged," Morrison said afterward. "It's one of those situations you have to live with and learn from it. I'll be back."

Morrison indeed came back, but he was never the same feared fighter. He beat a bunch of long shots and faded stars over the next couple of years before his loss to Lewis.

That fight happened in October 1995. By February, Morrison had tested positive for HIV.

He'd been preparing for another fight that winter when his blood test came back positive for the virus that causes AIDs. Morrison's license was quickly suspended by Nevada, and the ban was, in effect, upheld by every other sanctioning body. Morrison said at a news conference he'd never fight again, blaming his plight on a "permissive, fast and reckless lifestyle."

His lifestyle never changed, though, even when he stepped away from the ring.

He had already run afoul of the law in 1993, when he pleaded guilty to assaulting a college student. He also dealt with weapons charges and multiple DUI incidents over the years. He was finally sentenced to two years in prison in 2000, and another year was added to his sentence in 2002 for violating parole.

When he was released, Morrison said his HIV tests had resulted in false positives, and he wanted to resume his career. He passed medical tests in Arizona - even as Nevada stood by its decision - and returned to the ring.

Morrisoninvited the New York Times to test him for HIVin 2007.

That test, as well as two others for the sports sanctioning body in West Virginia, supported Morrison's assertion that he did not have the virus, the Times reported, although there was some doubt as to whether the blood provided for the tests was in fact Morrison's blood.

Morrison got in the ring two more times, once in 2007 in West Virginia and once in 2008 in Mexico, earning TKOs against lesser-known opponents.

His wife, Trisha Morrison, whom he married in 2011, saidin a recent interview with ESPN.comthat Morrison had Guillain-Barre Syndrome, not HIV.

Regardless, after the 1996 positive test, Morrison became a spokesman for a time for AIDS awareness and safe sex, creating the KnockOut AIDS Foundation, although it is unclear how active the charity is today.

He finished his boxing career with a record of 48-3-1 with 42 knockouts.

"Tommy's a very stubborn person and he views things the way he wants to view things. That's his right and privilege," Holden said. "All through his career, him and I would come not to physical blows but disagreements on certain things. We always ended up friends. That was Tommy.

"That's the way Tommy took off after he was told he was HIV-positive," Holden added. "When he first was told, I was taking him to seek treatment and to different doctors around the country. And then he started research on the Internet and started saying it was a conspiracy. He went in that direction and never looked back."

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