VISTA, Calif. -- A 16-year-old boy was one of three young gang members who fired from a concealed area at an Oceanside police officer, who died from a single gunshot wound, a prosecutor said Monday.

Penifoti Taeotui is charged with murder and special circumstances in the Dec. 20, 2006, death of Officer Dan Bessant, who had been working on a project to get rid of violence in the neighborhood where the shooting took place.

In his opening statement of trial, Deputy District Attorney Tom Manning said Taeotui, now 18, is charged with murder even though a fellow gang member, Meki Gaono, fired the shot that killed Bessant.

Gaono, Taeotui and a third gang member, Jose Compre, fired three different weapons from a dark area behind an 80-pound brick mailbox 386 feet from where Bessant was helping Officer Karina Pina with a traffic stop, Manning told the jury.

Gaono, now 19 and scheduled to go to trial Jan. 12, used a .22-caliber rifle with a scope to shoot Bessant under his left armpit -- just missing his protective vest -- striking his heart before exiting his body, the prosecutor said.

Bessant died at a hospital.

Manning called the shooting "senseless," carried out by gang members looking for revenge.

If gang members feel disrespected by police officers, "They will avenge," the prosecutor said.

Manning said Gaono, Taeotui and Compre were young gang members looking to commit crimes in order to gain status and respect in their gang.

"When they achieve it for the gang, they've also achieved it for themselves," Manning told the jury.

Defense attorney Will Rumble conceded that Taeotui -- known as "P.J." -- was a gang member, but insisted he wasn't involved in the shooting that took Bessant's life.

"My client did not kill Officer Bessant," Rumble told the jury. "P.J. did not shoot the gun that killed Officer Bessant."

Rumble said law enforcement investigating the shooting used pressure tactics to get five witnesses to say what they wanted to hear.

A District Attorney investigator told one witness, "And what you don't tell us is going to come back and bite you in the (expletive)," Rumble told the jury.

The investigator went on to tell the witness, "Don't (expletive) lie to me," Rumble said.

A gang member who prosecutors claim gave the murder weapon to Gaono and helped hide Taeotui after the murder was a "pathological liar," Rumble told the jury.

One witness told a detective that he felt the officer was trying "to make me say something that I don't want to say," Rumble said.

"These (five) witnesses are not credible," the attorney said.

Rumble said the gang evidence to be introduced by prosecutors won't prove that Taeotui is guilty of murder.

"It's not going to tell you whether Penefoti is guilty or not," Rumble said. "That's not what it's going to do."

Rumble said no evidence will be produced at trial that shows gang members think killing a police officer is the "ultimate act."

"It's frowned upon by gang members," Rumble said.

The attorney said prosecutors won't be able to prove that Gaono shot Bessant because officers were harassing the defendant's neighbors to "clean up their act."

"That's not a credible argument," the attorney said. "The evidence is going to reject that argument.

Rumble said Taeotui wasn't involved in the shooting and wasn't running around the neighborhood that night trying to escape.

The attorney said no witness will say that they saw the defendant shoot at the officer "(because) he didn't and there's no evidence to say that."

Rumble will finish his opening statement Tuesday, then the trial's first witnesses will be called.

After a 10-day preliminary hearing in March, Judge Runston Maino dismissed charges against Compre, saying there wasn't enough evidence for the case to go to trial.

Because he was a juvenile at the time of the shooting, Taeotui faces life in prison without the possibility of parole if convicted.

Besides murder and special circumstances of lying in wait and the killing of a police officer, the defendant faces assault charges for shooting at Pina and a civilian ride-along she had with her.

The trial at the Vista Courthouse is expected to last at least eight weeks.