John Travolta said Wednesday he tried desperately to save the life of his seizure-prone son as he testified against two people accused of trying to blackmail him with private information about the rescue effort.

With his wife Kelly Preston looking on inside the Nassau courtroom, Travolta said that he performed CPR on his son after a nanny alerted him the teen had fallen ill at a family vacation home on Grand Bahama island. Jett Travolta, whose father said he had autism, later died from a seizure.

"I ran downstairs with my wife to help my son," Travolta said.

Travolta is the star witness at the trial of two people — paramedic Tarino Lightbourne and former Bahamas senator Pleasant Bridgewater — who are accused of trying to extort $25 million from the movie star. Both defendants pleaded innocent to extortion charges at the trial that began Monday in this island chain off the Florida coast.

It was a rare public appearance for Travolta, 55, who has kept a low profile since Jett's death. He skipped promotional events this summer for his latest film, "The Taking of Pelham 1 2 3." He thanked his co-stars on his Web site for giving him time to grieve through their efforts to publicize the film.

Travolta arrived the Supreme Court building in an entourage of sport utility vehicles for his first appearance at the trial. Security was noticeably heavier than previous days with Bahamas police officers surrounding the courthouse.

In his testimony, he said he and Preston were awakened by a nanny around 10:15 a.m. on Jan. 2, the day of Jett's death. Travolta said when he went downstairs, another caretaker was doing chest compressions and he began administering breathing help.

Travolta said Jett, 16, was autistic and suffered seizures every five to 10 days. He said the seizures would last 45 seconds to a minute and Jett typically slept for 12 hours after each one.

"He was autistic. He suffered from a seizure disorder," Travolta told the jury when asked about his son's condition.

Police say the alleged scheme involved a document related to Jett's treatment. It would have released emergency responders from liability if the family refused an ambulance but police said that did not happen.

A police officer testified Tuesday that Travolta signed the release because he initially wanted his son taken to the airport instead of a local hospital.

A nine-person jury was expected to hear from a total of 14 witnesses, including Travolta