Responding to a reporter’s question, the lawyer said that Mr. Perrone had not expressed remorse.

Mr. Jones also said Mr. Perrone denied that he had killed anyone or had made incriminating statements to the authorities.

The first-degree murder count is a statutory charge available to prosecutors when three people are killed by the same person within two years. If convicted, Mr. Perrone would face life in prison.

Mr. Kelly said Mr. Perrone “had a minor criminal record” but did not elaborate. A spokesman for the Staten Island district attorney said Mr. Perrone had been convicted of drunken driving on at least one occasion more than a decade ago. Court records from Pennsylvania showed he had been arrested there in 2001 for charges that included harassment; that case was dropped by local prosecutors.

Like the three victims, Mr. Perrone worked in the retail industry. He was described as a kind of independent salesman, dropping in on shops around Brooklyn to peddle his wares. Mr. Kelly did not say whether Mr. Perrone had previous dealings with the men he was charged with killing, the most recent on Friday at a Flatbush Avenue women’s wear shop.

Each victim was an older man of Middle Eastern origin working alone in stores, the police said; none of the shops had video cameras. Mr. Kelly said Wednesday that Mr. Perrone had not been charged with bias crimes, and he declined to discuss a possible motive.

Robbery did not appear to be a motive, however — the most recent victim, Rahmatollah Vahidipour, 78, had $171 in his pockets when his body was found.

Mr. Perrone is divorced, and in recent years had been in “some difficulty” financially, Mr. Kelly said.