A 19-year-old charged in the slaying of a popular Dupont Circle area waiter was involved in at least three other armed robberies and possessed Social Security and other identification cards that were taken in earlier crimes, prosecutors said yesterday.

Kurt Williams lost his composure and began crying in D.C. Superior Court as prosecutors cited eyewitness testimony tying him to the killing early Monday of Adrien D. Alstad. Prosecutors said that a witness who was with Williams at the time of the killing saw him try to rob Alstad and then fire two shots at the victim at close range.

Another witness told police that Alstad said, "I don't have any money," when he was accosted at 2 a.m. in the 1800 block of R Street NW. The shooting took place just after Alstad, 55, had left work at Annie's Paramount Steak House nearby.

"He's been on a campaign of robbing citizens in this city, and when they don't give up the money he wants, he pulls a gun and shoots them," Assistant U.S. Attorney Colleen Covell told the court, arguing that Williams should be locked up pending trial on first-degree murder and other charges.

Williams, who upon entering the courtroom mouthed to his two brothers, "I didn't do it," moved suddenly toward the holding area after Magistrate Judge J. Dennis Doyle ordered him held without bond. Marshals surrounded him.

Williams, who lives with his aunt in the 200 block of R Street NW, was arrested Wednesday night moments after another robbery. In that crime, a witness called police to report a holdup in the 1800 block of Seventh Street NW.

Williams was taken into custody nearby, arrested in a T-shirt and underwear. His remaining clothes were on the ground next to him.

"The inference was that he was trying to change his appearance so he wouldn't match a lookout," Covell said.

Two youths, ages 15 and 16, who were with Williams on Wednesday night were charged in the robbery that evening. Prosecutors said they intend to try the 16-year-old as an adult.

Neither teenager was charged in Alstad's death.

In charging papers, prosecutors said a search of Williams's home turned up Social Security and other ID cards, including the Social Security card of a victim of a robbery a week earlier.

Covell said Williams is awaiting trial in Howard County on a charge of possessing a deadly weapon at a school. No details were provided.

Defense attorney Santha Sonenberg argued that Williams should be released because he has no previous convictions and contended that the case rests on the account of one purported eyewitness.

Police officials said Williams implicated himself in Alstad's killing during an interrogation Thursday, but prosecutors said nothing about his statements in court or in the charging documents.

Williams's brother Lawrence, 22, said outside the courtroom that his brother is religious and wanted to be a police officer when he grew up. "He had his little issues, but he was a good little brother," he said.

Staff writers Ylan Q. Mui and Del Quentin Wilber contributed to this report.

Adrien D. Alstad had just left his Dupont Circle job before he died.