Simpson was transferred to a detention center for booking Sunday evening. Simpson was reportedly cooperative. At least one other person has been arrested and police said Sunday that they were searching for four others in connection with the alleged armed robbery that occurred in a room inside the Palace Station casino-hotel on Thursday. Police Lt. Clint Nichols said Simpson invoked his right to an attorney immediately after being arrested. Simpson, 60, has said he and other people with him were retrieving items that belonged to him. Simpson has said there were no guns involved and that he went to the room at the casino only to get stolen mementos that included his Hall of Fame certificate and a picture of the running back with J. Edgar Hoover. Simpson told The Associated Press on Saturday that he did not call the police to help reclaim the items because he has found the police unresponsive to him ever since his ex-wife, Nicole Brown Simpson, and her friend, Ron Goldman, were killed in 1994.

"The police, since my trouble, have not worked out for me," he said, noting that whenever he has called the police "It just becomes a story about O.J." Police said two firearms and other evidence were seized at a private residence early Sunday.Walter Alexander, 46, of Arizona, was arrested Saturday night 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.He was released without bail on Saturday night, Dillon said.Besides the two firearms, police said they seized other evidence during early morning searches of two residences, Lt. Clint Nichols said."It was evidence of a crime that was committed," Nichols said. "And I believe we recovered some clothing that the individual was wearing in the commission of the robbery."

Simpson said auction house owner Tom Riccio called him several weeks ago to say some collectors were selling some of his items. Riccio set up a meeting with collectors under the guise that he had a private collector interested in buying Simpson's items. Simpson said he was accompanied by several men he met at a wedding cocktail party, and they took the collectibles. Alfred Beardsley, one of the sports memorabilia collectors involved in the alleged robbery, has said he wants the case dropped and that he's "on O.J.'s side. "Nichols said police had a responsibility to investigate how the collectibles were taken, regardless of who they belong to. "We don't believe that anybody was roughed up, but there were firearms involved in the commission of the robbery," he said. The Associated Press contributed to this story