NEW YORK, APRIL 19 -- A career criminal testified today that accused murderer Joseph Fama told him in jail last month that he had shot and killed a black teenager on a Bensonhurst street but boasted that he would beat the charge by feigning insanity.

In the first testimony tying Fama, 19, to the racially charged murder of Yusuf Hawkins last summer, Charles Brown quoted Fama as telling him in the Brooklyn House of Detention, "I shot him. I shot him. I can't bring him back."

According to Brown, Fama told him he had been in a car accident at age 4 and that "my lawyers will take care of it. I'm going to plead insanity . . . . I'm just going to play like I'm crazy, like I don't know what happened." Fama has not invoked such a defense.

In an aggressive cross-examination, Fama's lawyer, Joseph DePetris, questioned whether his client would tell Brown, who is black, of the shooting on the first day that they met.

Brown said the conversation occurred the day after he was transferred to the Brooklyn jail and while he was telling Fama that they should get along, even though Fama was "in prison for something that's very bad."

A bearded man who appeared in a gray suit provided by the prosecution, Brown said he has used a half-dozen aliases and has been in prison almost continuously since 1974 on rape, robbery and drug charges. He admitted that he has used drugs in prison and said most of his friends are drug dealers.

Under sharp questioning, Brown acknowledged that he has acted repeatedly as a jailhouse informant in what DePetris called "high-profile media cases." Brown said he testified against the killer of a Pratt Institute art student and a Queens drug dealer accused of ordering the murder of his parole officer.

Brown, who has been moved to a safe house, acknowledged that he had read extensively about the Bensonhurst case before meeting Fama. He said Brooklyn prosecutors had promised only to notify parole authorities of his cooperation and that, in any event, he is scheduled for release in October.

About a week after the alleged confession, Brown testified, Fama confronted him and said he had heard from his uncle that "there's a rat on the case." Brown said he told Fama that he was not the informant.

"My father said if the guy was wired, I'm dead," Brown quoted Fama as saying. "If the guy was not wired, he told me, don't worry about it."

DePetris said in a hallway interview that "I can't believe for a minute anyone would believe it, the first day he meets my client."

Later, Phyllis D'Agata, a key prosecution witness, testified that she saw Fama's codefendant, Keith Mondello, on the night of the shooting with a baseball bat in one hand and a gun in his waistband. She said she heard threats from Mondello and his friends about shooting blacks.

D'Agata is the mother of Gina Feliciano, the Bensonhurst girl who may have triggered the Aug. 23 confrontation by inviting black and Hispanic friends to her birthday party. Fama, Mondello and several other Bensonhurst men are charged with attacking Hawkins and three black friends in the mistaken belief that they were Feliciano's guests.

Under cross-examination by Mondello's lawyer, Stephen Murphy, D'Agata admitted she had changed her story several times about what she saw from her apartment window. D'Agata variously said she saw the gun in Mondello's pocket, in his waistband or just the outline of a weapon under his clothes.