Actor John Travolta is a key prosecution witness in the trial of two people accused of trying to extort $25 million US from him soon after his teenaged son died in the Bahamas.

The extortion case is expected to begin Monday in Nassau, Bahamas, with jury selection.

Bahamas Chief Magistrate Roger Gomez confirmed the actor is on a list of witnesses. Travolta will probably have to take the stand because he filed the extortion complaint, which under Bahamian law obliges him to testify in person.

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Jett Travolta, shown in an undated photo, died from a seizure at the family's vacation home in the Bahamas on Jan. 2. ((Rogers & Cowan/Associated Press))

An ambulance driver and an Bahamian ex-politician are alleged to have tried to squeeze money from Travolta after his son Jett, 16, died from a seizure Jan. 2 at the family's vacation home in the Bahamas.

According to police, paramedic Tarino Lightbourne kept a one-page "refusal to transport" form that Travolta had supposedly signed. The document frees the ambulance crew of liability if a patient declines to be taken to a hospital.

About  two weeks later, Lightbourne's lawyer, Pleasant Bridgewater, contacted Travolta's attorney and said her client wanted to sell the document to the movie star, Bahamian police allege.

Lightbourne and Bridgewater, a former Bahamian senator, have pleaded innocent to the charges, which include conspiracy to commit extortion.

On Sept. 11, the 55-year-old actor, his wife, Kelly Preston, and daughter Ella Bleu made their first public appearance since Jett's death at an event in Anaheim, Calif., to promote the upcoming film Old Dogs, in which they all star.

In August, Preston pulled out of California's annual Women's Conference, where she was expected to break her silence about her son's death.

The actress released a statement that she was "still deeply in the process of healing, and it's just too soon."

Preston was slated to participate in a panel on grief at the October event hosted by Gov. Arnold Schwarzenegger and his wife, Maria Shriver, in Long Beach, Calif.

With files from The Associated Press