1 Convicted, 2 Acquitted in Slaying of Youth, 16 : Courts: Conviction carries term of 15 years to life for Long Beach Polytechnic High student. The murder attracted nationwide attention.

A classmate of the victim in the notorious slaying of a Long Beach teen-ager was convicted of second-degree murder Wednesday while two other youths were acquitted.

Eighteen-year-old Mike McDonald, who collapsed, sobbing, as his guilty verdict was read, was the only one of three Polytechnic High School students to be found guilty in the death of Alexander Giraldo, 16.

The jury in the case acquitted his co-defendants, Schuyler MacPherson, 19, and Bryan Davis, 18.

Giraldo’s death attracted nationwide attention when police linked the killing to the Ace of Spaces, a rogue paramilitary gang that arose among students at Polytechnic High School in Long Beach.

The four teen-agers were arrested after a four-month investigation into the death of Giraldo, whose body was found Feb. 2, 1992, at the bottom of a San Pedro cliff.

The boy, police said, had been strangled with wire and stabbed in the neck with a stick, which severed his jugular vein.

The case gained notoriety after investigators linked the killing to a secret club at the school.

Police speculated at the time that Giraldo had been killed because he had told authorities about a series of auto burglaries that he and another club member had committed. In interviews, members of the club acknowledged that they had committed crimes, including vandalism, car burglaries and assaults.

But at the trial, defense lawyers argued that the defendants did not belong to the gang. Prosecutors, meanwhile, downplayed the Ace of Spades association, focusing instead on circumstantial evidence and the testimony of a 17-year-old witness, who took the stand in exchange for a reduced sentence and who was the only witness to step forward.

The witness, whose name was withheld because of his age, testified that he and the three defendants had killed Giraldo on Feb. 1, 1992. The youth testified that Davis and McDonald took turns strangling the victim with a wire noose while MacPherson waited in a car.

But defense attorneys attacked the witness’ credibility, arguing that the real killers were, in fact, members of the Ace of Spades, and the witness--who they said was also a member--had implicated himself in the murder because he feared retaliation.

Defense attorneys also produced alibis, which were disputed by the prosecution, for Davis and MacPherson. They called Davis’ older brother, who testified that the two youths never left the Davis residence for more than 30 to 60 minutes Feb 1. The lawyers argued that this was not enough time to commit the crime.

No such alibi was offered for McDonald, however, and one juror, who requested anonymity, attributed his conviction to that gap in the defense.

The juror also said that the key witness was not believable.

“They say: ‘Take some things with a grain of salt,’ ” said the juror. “I think you needed to take a cup of salt with him.”

And, the juror said, the panel was influenced by testimony that Ace of Spades members had beaten Giraldo twice in late December, allegedly for stealing from gang members and cooperating with police in the investigation of car burglaries involving the gang.

McDonald was present at one of the beatings, but MacPherson and Davis were not, a factor that the jury considered important, the juror said.

McDonald--whose mother shrieked and ran weeping from the courtroom when her son’s conviction was announced--faces a sentence of 15 years to life in prison. Sentencing is scheduled for June 2 in Long Beach.

Luis Giraldo, the father of the murder victim, said he was bitterly disappointed with the verdict.

“America is the only place where people can get off for murder,” he said.

Down the hall, however, MacPherson embraced his mother and his attorneys.

“I’m happy it’s over,” MacPherson said. “I’m sorry Mike is convicted. I don’t believe he did it.”

Times staff writer Shawn Hubler contributed to this story.