One of the collectors was Bruce Fromong of North Las Vegas, a former Simpson business partner who had hoped to sell some memorabilia that included items signed by Simpson and other sports stars such as Joe Montana.

He said he expected a potential buyer to walk into the Palace Station hotel room when Simpson and several other men entered instead. One of the men stuck a gun in his face, but Fromong instead stared at Simpson.

"I kept looking at O.J. thinking, 'How stupid can you be, Juice?'" Fromong said. "If I was going to do something like that, I'd be sitting out in the parking lot and letting my guys take care of it. How stupid can you be. ... You've got enough trouble. You're O.J. Simpson, for God's sake."

Simpson left with more than $75,000 in sports memorabilia, Fromong said.

Simpson told The Associated Press that he took the memorabilia, but only because it had been stolen from him.

"We didn't break into any room. There was no armed robbery," the 60-year-old Heisman Trophy winner said. "Nobody was roughed up. What I can't understand is these guys are in a room trying to fence stolen goods, and I'm the story."

But a source close to the investigation said Simpson's entourage was armed and took the memorabilia by force.

"We do believe a robbery occurred, and O.J. was part of it," the source said. "He went there with goons who were armed."

Las Vegas police responded to the hotel about 8 p.m. Thursday. Simpson cooperated with investigators with "no hesitation at all" that night and on Friday, although he would not give a full statement until his lawyer got to Las Vegas, said Capt. James Dillon of the Robbery/Homicide Bureau.

Police had not made any arrests in the case late Friday.

Simpson's lawyer, Yale Galanter, had no comment, his Florida office said.

Detectives had not found any weapons but did recover at least some of the memorabilia in dispute, Dillon said. They hoped to interview all witnesses or suspects within the next few days as part of the investigation, he said.

Investigators have reason to believe Simpson's story -- that some of the memorabilia had been stolen from him, but he never reported it to police, the source said.

"Even if the property was his, that doesn't excuse him from taking the property," the source said.

Detectives were looking into whether the confrontation was a setup engineered by auction house owner Thomas Riccio, who brokered the meeting in the hotel room, the source said.

Fromong and the second collector in the room, Alfred Beardsley of Burbank, Calif., believe it was.

"It was an absolute setup, and Simpson confirmed to me it was a setup," said Beardsley, who said he had a "decent conversation" when Simpson called him Friday afternoon.

Beardsley is a longtime collector of Simpson memorabilia, although whether he owned the items taken Thursday was in dispute. Police listed Beardsley as the property owner, but Fromong said the stuff was his.

Fromong, who sells sports memorabilia on eBay under the name Superbowl Kid, said Riccio called him about a buyer interested in his collection. When Fromong met Riccio at Palace Station, Riccio convinced him to bring his collection to the room, he said.

Riccio left to get the buyer, and a minute later five men in suits and Simpson burst through the door, he said.

Fromong said he saw one gun, maybe two.

"It was pointed right in my face," the 53-year-old said. "Hard to miss."

When Simpson first saw his old friend, he seemed startled, Fromong said. Then the football star accused Fromong of stealing, he said. Simpson and Fromong exchanged words, but Fromong would not repeat what was said.

The men with Simpson collected the memorabilia, including six or seven footballs and three plaques given to Simpson, along with items signed by Montana and baseball greats Duke Snyder and Pete Rose, Fromong said.

Some of the memorabilia once belonged to Simpson, but Fromong said he had purchased it from someone close to Simpson and could prove it. Fromong said he even paid Simpson to autograph some of the items.

"He took stuff that had absolutely nothing to do with O.J.," including Fromong's cell phone, Fromong said. "They took everything. All of it was my stuff."

Beardsley said the confrontation was nerve-racking.

"Things just got really, really heated last night when this went down," he said. "It was a dangerous situation. It was a scary, scary thing."

Riccio did not return a phone call made to his office.

But Riccio told the Los Angeles Times that he arranged the meeting after receiving a phone call about a month ago from a person who claimed to have personal items -- including footballs, awards and personal photos -- that had belonged to Simpson and wanted to sell them.

"Simpson was supposed to show up, identify the items and tell the men to either give the stuff back or he would call the police," Riccio told the newspaper.

The plan unraveled after Simpson showed up with a group of "intimidating looking guys," at least one of whom had a gun, he said.

"We tried to peacefully reacquire these personal items," Riccio said.

"They (Simpson and his companions) took the stuff, and they left. What can I say? Things went haywire," he said.

Fromong, who had worked for Simpson selling his sports memorabilia for years, said Simpson took the coward's way out and wishes he had simply asked for his items.

Simpson had been a friend who once called Fromong to offer condolences the day after his mother was killed by a drunken driver. No longer.

"I lost a good friend last night," he said.

Simpson was acquitted of murdering ex-wife Nicole Brown Simpson and her friend Ron Goldman in 1994. Simpson was defended in the so-called Trial of the Century by a cadre of high-profile attorneys, including F. Lee Bailey and the late Johnnie Cochran, dubbed the Dream Team.

Fromong testified at the wrongful death civil trial in which Simpson was found liable for the slayings.

The Goldman family on Thursday released "If I Did It: Confessions of the Killer," a book written by Simpson but owned by the Goldmans to help satisfy a $38 million judgment from the civil trial.

The Goldmans' San Francisco lawyer, David Cook, said Simpson's involvement in the robbery case would help spark sales, but he accused the former football star of trying to steal the spotlight from the book release.

Cook said he planned to file a motion Tuesday in a Los Angeles County court to claim the disputed memorabilia. If it belongs to Simpson, the Goldmans can take it as payment toward the judgment.

"It is a bizarre twist of fate," Cook said. "If Mr. Simpson prevails, we cheer him on."

The Associated Press contributed to this report.