A 26-year-old man who police said was a heroin addict with a long criminal record was identified yesterday by police and prosecutors as the murderer of a press secretary to Mayor Giuliani.

The former Giuliani aide, Martin Barreto, 49, was a graduate of Brown University and Columbia Journalism School who was discovered dead on August 21, naked on his bed in his West 10th Street apartment in Manhattan.

Authorities said Barreto had apparently struck up a conversation with a stranger on the streets of Greenwich Village the night he was killed. The young man accompanied Barreto home.

Detectives apprehended Edwin Ramos Tuesday around 3:30 p.m. at a Manhattan employment agency on Park Avenue, where the suspect turned up to collect back pay for six weeks’ work in July and early August. After Ramos attempted to flee, detectives chased him for two blocks down Park Avenue and cornered him near East 32nd Street, police said.

Once in police custody, Ramos “implicated himself, but said he didn’t mean it,” according to Deputy Inspector Bernard Cosenza, of Manhattan South’s Detective Squad. According to Inspector Cosenza, Ramos said he met Barreto randomly on the street, and Barreto invited him to his apartment. Before his arraignment last night, prosecutors said they intended to charge Ramos with second-degree murder, reflecting his alleged intent to kill.

Barreto’s body was found after a friend told his doorman and police that Barreto wasn’t responding to phone calls or knocks on his door. Detectives found a condom wrapper and lubricant near his body, and an autopsy indicated he had been strangled to death.Yesterday, detectives confirmed Barreto’s killer took the victim’s laptop, cell phone, and some clothes before leaving the apartment.

Police declined to say what evidence in particular led them to Ramos, who worked for Temco Service Industries for six weeks, according to a spokesman for the company.

But police said Ramos had previously racked up an extensive criminal history. Most recently, he was sentenced in September 2003 to two years in a Puerto Rican prison for criminal possession of stolen property, unlawful imprisonment, and criminal possession of a weapon, police said. At the time of those charges, Ramos was already in law enforcement custody after being charged with improper use of vehicle parts earlier that month.

Police said Ramos had also been arrested in Puerto Rico in 2000 for petit larceny, and in 1999 for criminal possession of a controlled substance. Police said that before that, Ramos was arrested on drug-related charges in Minnesota in 1998 and 1999. Records from the department of corrections there do not indicate he served time in prison.

Those close to Barreto said it was unlikely he knew of Ramos’ past when he invited him upstairs to his apartment the night he was killed. “It seems very much out of character for Martin,” his business partner, Roxanna Brightwell, said. “I don’t know if Martin had befriended this man and was trying to help him when he may have turned on him.”

Barreto served as an assistant press secretary and a Hispanic affairs liaison at City Hall between 1994 and 1996. He was a spokesman for the Department of Consumer Affairs through 1997. The former radio journalist was active in the National Association of Hispanic Journalists, and co-founded his own communications firm, Barreto and Brightwell Associates, in 1998.

Yesterday, Ms. Brightwell said she knew little about Barreto’s love life but said she was sure his death was a homicide. “If it had been an accident and this person had been an honorable person, he would have turned himself in,” she said. “But this person left with anything that would trace him: cell phone, Martin’s laptop, and I believe his keys,” she said.

Family members said the arrest provided a taste of resolution for them. Barreto’s brother-in-law, Richard Meyer, said that if Ramos “is, indeed, the culprit, we’re glad he’s off the street.” He said, “It is gratifying that there may be some closure on that front.”