Closing Arguments Focus on Youth’s Testimony in Killing : Trial: Prosecution says the 17-year-old, who is not charged in the case, is credible enough to incriminate the others. Defense says teen-ager is framing three defendants.

The prosecution Friday called its main witness a liar and murderer, but credible enough to incriminate three alleged teen-age accomplices in the execution-style slaying last year of a 16-year-old classmate.

The witness, a 17-year-old whose name is being withheld because of his age, has testified that he committed the murder along a desolate San Pedro cliff with defendants Schuyler MacPherson, 19; Bryan Davis, 18, and Michael McDonald, 18.

The three are charged with strangling and stabbing Alexander Giraldo, a classmate at Polytechnic High School in Long Beach.

The witness said he attacked Giraldo because Giraldo had told police about the juvenile’s involvement in a car burglary. The prosecution did not introduce evidence about the motives of the three defendants.

The defense team at the Long Beach trial blamed the killing on the Ace of Spades, a paramilitary youth gang, but said their clients are not members.

In closing arguments, defense attorneys pointed out numerous contradictions in the witness’s testimony. They said he was framing the defendants.

Giraldo’s death attracted nationwide attention when police linked the killing to the Ace of Spades, which arose among Polytechnic ROTC students. In interviews, gang members claimed to enjoy war games and admitted to committing crimes for kicks.

But when the case came to trial last month, prosecutor Ken Lamb avoided the Ace of Spades association. He argued instead that the evidence showed that four teen-agers--his witness and the three defendants--brutally killed a schoolmate.

Lamb said his witness had lied in the past to minimize his role in the killing. But the prosecutor argued that corroborating evidence, combined with common sense, supported his witness in two essential details: The juvenile was involved in the killing and he and the defendants were together at the time.

To disbelieve the witness, “you have to find he admitted a crime for no reason,” Lamb told the jury. “That doesn’t make any sense at all.”

Defense attorneys have attempted to show that the juvenile confessed to a murder he did not commit. They said the juvenile implicated the defendants because he feared the real killers, the Ace of Spades.

“If he tells who the true killers are, is he going to end up like Alex, found on the edge of the cliffs?” asked attorney Leonard Matsuk, who represents Davis.

Matsuk noted that the witness had testified to being afraid of the Ace of Spades. He “is only afraid of them, I suggest to you, because he knows too much. He is certainly not afraid of these fellas,” Matsuk said, motioning toward the defendants.

McDonald’s attorney, Chris Ayers, reiterated the point by pointing out that MacPherson and Davis were honors students. Defense attorneys suggested that the juvenile confessed to avoid prosecution for other alleged crimes. They also noted that in exchange for taking the stand, the 17-year-old served only about 11 months in a juvenile detention facility for his confessed role in the slaying.

In testimony that covered two days, the juvenile gave this version of what happened:

On the day of the killing, the juvenile and McDonald fashioned a noose from musical instrument wire in McDonald’s garage. They stopped by a movie theater to gather ticket stubs for an alibi after joining Davis and MacPherson.

MacPherson, who was driving, dropped off the juvenile at the cliff while the other three picked up Giraldo from his Long Beach home.

The three defendants returned with Giraldo. While MacPherson stayed in the car, the others joined the juvenile, who knocked Giraldo to the ground. Davis and McDonald took turns garroting Giraldo with the wire until he lay motionless. The three dragged him to the cliff’s edge and rolled him over the side.

Just before they drove away, McDonald double-checked that Giraldo was dead, returning to the car with a bloody knife, the juvenile said.

A jogger found Giraldo’s body in a ravine the morning of Feb. 2. The coroner’s office concluded that Giraldo had died from strangulation and a stab wound to the neck.

The defendants did not testify, but in statements to police, they said MacPherson and Davis dropped off McDonald and the juvenile at the movies and later picked them up. Davis’ brother testified that Davis and MacPherson had spent all but a brief portion of the evening at the Davis residence.

The heart of the prosecution’s case is the testimony of the juvenile because no other witnesses have come forward. Other evidence is circumstantial, such as phone records of calls from Giraldo to Davis on the night of the killing and testimony that Giraldo told a friend that MacPherson was going to pick him up that same evening.

Police also found on Giraldo’s body a remote control that operates the compact disc player in MacPherson’s car. MacPherson could not locate his remote.

In McDonald’s garage, police uncovered guitar wire similar to the bloodstained wire retrieved from near the body. Police said they believe that Giraldo died before midnight, and MacPherson’s mother saw her son and Davis vacuuming MacPherson’s car a few hours later. Margaret MacPherson said the cleaning was not unusual, and defense attorney Matsuk argued that cleaning cars is a male teen-age obsession.

Defense attorney Ed George, who represents MacPherson, concentrated on motive, saying it was illogical to believe that MacPherson “would kill his best friend.”

While attacking Lamb’s case, the defense tried to mount its own prosecution of the Ace of Spades. They called Giraldo a member of the gang--a charge denied by Giraldo’s family--and said the prosecution’s witness also belonged to the group.

Defense attorneys said members of the Ace of Spades beat up Giraldo twice in late December, allegedly for cooperating with police in the investigation of car burglaries involving the gang.

Prosecutor Lamb successfully fought to exclude most evidence about the Ace of Spades, arguing that details about the the group were irrelevant unless the defense could produce evidence of the gang’s involvement.

The jury begins deliberations Monday. The defendants face a maximum sentence of 25 years to life in prison.