Golfito, Costa Rica ? Testimony against three people accused of killing Kansas University student Shannon Martin was conducted in private, closed-chamber proceedings Friday morning after two anonymous telephone death threats to the prosecutors’ office warned the witness would be killed if she took the stand.

Police officers armed with M-16 assault rifles guarded the courtroom as the witness, identified by a Martin family lawyer as Rosibel Munoz, was sworn in and delivered testimony against primary murder suspect Kattia Cruz, 29, who also is known by the street name La Panteonera (“The Grave Robber”).

Shortly before Munoz was scheduled to testify, the courthouse office of the prosecutor received a call saying, “If Rosibel testifies, we’ll kill her,” prosecutor Erick Martinez said. Lawyers claimed other witnesses also have received threats.

Martin, a 23-year-old honors student, was stabbed to death May 13, 2001, after leaving a nightclub in this southern Pacific port town about 100 miles south of the Costa Rican capital, San Jose. Martin was in Costa Rica to gather specimens for a biology project.

According to court documents, Munoz, Cruz’s neighbor, said she saw Cruz leave home the evening of the crime wearing a black T-shirt emblazoned with the words “L.A., Los Angeles,” and return home in the early-morning hours with the shirt ripped and tied around her breasts. Torn strips of a black T-shirt with the letters “L.A.” were found at the scene of the crime.

Munoz is a resident of Rio Claro, seven miles north of Golfito.

Two other suspects, Luis Alberto Castro Carrillo, 33, and Rafael Zumbado Quesada, 52, also are standing trial for Martin’s death.

Friday’s proceedings opened with the prosecution calling to the stand two of the investigating officers who conducted a yearlong probe into the slaying. Both said all of the evidence collected pointed toward the three suspects on trial.

Their testimony highlighted the fear felt in the community. Both officers told judges that many people called them in the months after the crime to name the killers, then would hang up without identifying themselves. The same three suspects were consistently identified, the officers testified.

Janet Stauffer, left, and Jeff Thomas, right, look at photos of Shannon Martin. The two were in Costa Rica Friday for the trial of three suspects charged with killing Martin.

One witness, Seidy Hernandeztestifiedthat she served as a middleman as Cruz tried to sell one of Martin’s earrings. The earring is being used as evidence in the trial.

In the afternoon, Mart–nez asked the three-judge tribunal to enter as evidence a videotape of the autopsy. The judges accepted the evidence and suspended the trial until Wednesday, when the tape will be viewed.

Esteban Madriz, a taxi driver who allegedly drove Cruz and Castro from the area where Martin was killed to a gas station, was scheduled to testify Friday but never appeared. The court ordered a search for him.

An agent with the Kansas Bureau of Investigation, Larry Thomas, who helped Martin’s family gather evidence and locate witnesses, will not testify as expected, said Juan Carlos Arce, a lawyer representing Martin’s family, because he is acting as part of the prosecution team.

Closing statements will be heard Nov. 24, after which the judges will have 48 hours to hand down a verdict.

¢ 6News video: Threats alleged against Martin case witnesses¢ Witness: Slaying suspect confessed (11-14-03)¢ 6News video: Witnesses say that suspects confessed to Martin’s murder (11-14-03)¢ Testimony details fierce attack (11-13-03)¢ 6News video: The trial in Shannon Martin’s killing will begin soon¢Past stories, video reports