The main suspect in the investigation into the murder of Maltese journalist Daphne Caruana Galizia has demanded immunity in exchange for disclosing what he knows about the case, sources close to the file said Saturday.

The suspect, Jürgen Finnish, has sought judicial immunity as the Maltese police continue to question him at their headquarters about his alleged involvement in the assassination.

According to police sources, the businessman, Finish, then complained of pain and was taken to hospital for treatment. His health was not known.

The presumed mediator, who was the reason for the suspension, was a 41-year-old taxi driver, Melvin Thoma, who was also taken to hospital on Friday after complaining of pain. A few hours later, he was discharged from hospital and taken to police headquarters for questioning.

The suspect, Finish, was arrested on Wednesday on his yacht as he tried to flee the Mediterranean archipelago.

He is formally considered to be a person with information about the case.

At present, he requests judicial immunity or some sort of arrangement to inform the police of what he knows about the crime, which may lead to the disclosure of other persons involved in the case.

Maltese Prime Minister Joseph Moscat, who granted immunity to the driver, was charged with accepting or rejecting the request in exchange for providing information about the crime.

Galizia was killed by a car bomb placed under her car on October 16, 2017.

"The situation is miserable, and the crooks see them wherever you take your face," the journalist wrote a half-hour before her death, criticizing Chief of Staff Keith Shambari, who is under investigation for corruption.

Daphne ranks as one of the leading investigative journalists in recent years and has been involved in the Panama Documents investigations and has been interested in uncovering the corruption surrounding offshore companies in her home country.

The journalist exposed mysterious aspects of Malta's political life and violently attacked the prime minister, accusing him of making Malta a "mafia island."