Golfito, Costa Rica ? A defendant on trial for the murder of Kansas University student Shannon Martin has been jailed after allegedly threatening a witness, officials said Friday.

Luis Alberto Castro Carrillo was accused of hitting and threatening to kill witness Daniel Flores Mosquera, according to court officials.

Attorneys are scheduled to begin final arguments on Monday in the trial of Castro, 33; Kattia Cruz Murillo, 29; and Rafael Zumbado Quesada, 52.

While the other two defendants have been in jail, Castro had been allowed to remain free pending a verdict by the three-judge panel.

On Tuesday, Martin’s mother, Jeanette Stauffer, of Topeka, Kan., received death threats at the hotel where she is staying along with other family members, said Raul Quesada Galagarza, head of law enforcement authorities for southern Costa Rica.

Martin, a 23-year-old student from Topeka, was stabbed to death on May 13, 2001, after she left a nightclub in Golfito. She was in the country to gather specimens for a biology project.