His wife, Lynette Fromong, says Simpson is at fault.
"So you don't point a gun at my husband's head and have me fearful all night and then have me go, 'Oh, well, it was just something that went wrong,' she told CBS News correspondent Jeff Glor. "I'm certainly convinced that he is behind bars because he deserves to be there."
Hours before his heart attack, Fromong told The Early Show he was robbed at gunpoint and, by most estimates, held for at least six minutes by a group Simpson was leading.
"When he came in with the first two men, the second man already had his weapon drawn, which was a bit scary," Fromong told The Early Show co-anchor Julie Chen on Monday. "O.J. was the last person ... through the door. When he came through, you could see him. He stopped for a second. He wasn't expecting to see me there. I've known O.J. for a long time. He definitely wasn't expecting me and I definitely wasn't expecting O.J."
Simpson called Fromong on Saturday, and in a tape of that conversation obtained exclusively by CBS News, Simpson tells his side of the story.
CBS Legal Analyst Mickey Sherman says that Simpson could have been set up.
"It's so hard to tell who the really bad guys are here," Sherman told The Early Show co-anchor Harry Smith. "It's not good guys versus bad guys. It's bad guys versus worst guys. There's no boundary as to who is the real deal."
"O.J. is sounding like an innocent man, I have to tell you, up until his arrest," Court TV anchor Lisa Bloom added. "He went in to get his stuff, he accidentally took some extra stuff. He's giving it back. He's doing interviews because clearly he didn't think he would be arrested."
Meanwhile, authorities say a third man suspected of barging into a hotel room with Simpson to steal sports memorabilia has been arrested.
Las Vegas police Lt. Clint Nichols says Clarence Stewart surrendered Monday at his lawyer's office.
CBS News correspondent Steve Futterman reports Stewart, 53, is said to be a golfing buddy of Simpson's.
Police say Stewart lived at one of the residences that police searched early Sunday to recover sports memorabilia taken in the alleged Thursday night heist. According to Nichols, Stewart turned over some of the missing goods, including footballs bearing autographs.
Stewart is being held on six felony charges: two counts of robbery with a deadly weapon, two counts of assault with a deadly weapon, burglary with a deadly weapon and conspiracy.
Simpson is being held at the Clark County Convention Center in Las Vegas without bail pending a Wednesday arraignment and hearing revisiting the question of what charges he ultimately will face and the issue of whether he can be released from jail while fighting those charges.
Simpson claims he was retrieving collectibles that were first stolen from him, and that the raid was part of a sting operation.
The first suspect to be arrested, Walter Alexander, 46, of Mesa, Ariz., was taken into custody Saturday on two counts of robbery with a deadly weapon, two counts of assault with a deadly weapon, conspiracy to commit robbery and burglary with a deadly weapon. Alexander, described as being one of Simpson's golfing buddies, was released Saturday night -- without bail.
Las Vegas police Capt. James Dillon says Alexander was one of two men involved in the incident who had a gun.
Dillon says two other suspects are in the process of hiring attorneys and preparing to surrender to police.
Sports memorabilia collectors say Simpson and others stormed into their room at the Palace Station hotel and casino Thursday in Las Vegas, threatened them with weapons, and stole from them.
Police say Simpson was booked at the county jail Sunday night on two counts of robbery with a deadly weapon, two counts of assault with a deadly weapon, and conspiracy to commit a crime and burglary with a firearm.
The district attorney says he expects Simpson to be charged with seven felonies -- including robbery charges carrying sentences of as much as 30 years per count -- and one gross misdemeanor.
"If there's a conviction," says CBS News legal analyst Andrew Cohen, Simpson could be looking at serious time behind bars. "Whenever you're dealing with armed burglary, you're dealing with a very serious felony that has a very long prison sentence attached to it."
Police said they are giving Simpson no special treatment -- other than keeping him separated from the rest of the general prison population for his own protection.
A lawyer for Simpson, meanwhile, has gone on the offensive.
Defense attorney Yale Galanter says prosecutors lack the evidence to prove that the former football star committed armed robbery and other felonies.
"We are definitely on the attack," says Galanter, a Miami attorney who flew to Las Vegas to appear on Simpson's behalf.
Galanter plans to seek Simpson's release on his own recognizance. Simpson, says Galanter, had offered to surrender even if he had to return from his home in Miami, but police instead chose to arrest him.
"If it was anyone but O.J. Simpson, he would have been released by now," says Galanter, who maintains that witness statements will clear Simpson.
Simpson told The AP before his arrest that there was no gun involved and he was only retrieving items that had been stolen from him, including his Hall of Fame certificate and a photo of himself with former FBI chief J. Edgar Hoover.
"You can't rob something that is yours," says Galanter. "O.J. said, 'You've got stolen property. Either you return it or I call the police."'
Galanter acknowledges that the use of a gun would change the situation but he said Simpson was not armed.
Loyola University Law Professor Laurie Levenson says the legal definitions would likely be disputed at a trial but she said the case seems to have been overblown.
"It seems like an awful lot of charges for what happened," says Levenson, who was one of the legal analysts covering the O.J. Simpson murder case more than a decade ago.
One bit of evidence confronting investigators and Simpson's defense lawyer is an audiotape released Monday by the celebrity news site TMZ.com, in which a man believed to be Simpson is heard shouting questions while other men yell orders to the people in the room.
The tape -- purportedly of Simpson in the hotel room Thursday talking to the men he accused of stealing memorabilia from his football career -- begins with the ex-NFL star demanding, "Don't let nobody out of here."
"Think you can steal my s--- and sell it?" says a voice identified as Simpson's.
The recording was made by Thomas Riccio, co-owner of the auction house Universal Rarities, according to TMZ. Simpson has said Riccio called him several weeks ago to tell him collectors were selling some of his items.
Riccio told TMZ he believed Simpson was planning to confront Alfred Beardsley, who was allegedly planning to auction the memorabilia.
Riccio, according to "Entertainment Tonight" and "The Insider," received a voicemail message from Simpson in which Simpson says: "Hey, man, Tom, it's O.J. What are they talking about a gun? … Ain't nobody have any gun, what does that ... come from? I guess they feelin' guilty, so they try and make up something. Alright man, call me. Please."
Riccio's answer to that is not good news for Simpson.
"I did see a gun," Riccio told an "E.T." and "Insider" reporter, "and I told him that 'O.J., I saw a gun and I can't lie about nothing, you know, basically maybe you didn't see a gun.' "
The key question is why that tape even exists, said Bloom. Why did the tape get sold to a celebrity Web site rather than going to the police?
One of the other challenges for prosecutors in the case will be determining who actually owns each of the pieces of sports memorabilia, including Joe Montana's shoes and Simpson's Hall of Fame certificate.
Ownership is going be disputed in yet another way by Fred Goldman, who is filing to have items owned by Simpson turned over to him, including any memorabilia seized by police and the gold watch and suit Simpson was wearing when acquitted of the murders of his wife, Nicole Brown Simpson, and Goldman's son, Ron Goldman.
Goldman is seeking ownership to satisfy the terms of a $33.5 million civil court judgment against Simpson, who lost a 1997 wrongful death lawsuit filed by the Goldman and Brown families.
"Assuming that this case is resolved one way or another, at the end of the case, the stuff will never go back to Mr. Simpson," says David Cook, an attorney for Fred Goldman. "He's going to walk out of Clark County empty-handed."