The widow of taxi driver Manh The Nguyen, murdered in July 2006 at the Tantalus Lookout, has sued his alleged killer, Adam Mau-Goffredo.

Mau-Goffredo has been found to be mentally unfit to stand trial in the murder case. He suffers from paranoid schizophrenia and is undergoing treatment at Hawai'i State Hospital.

The lawsuit filed by Nguyen's widow, Cynthia Lai, also names Mau-Goffredo's guardian, William R. Carroll Jr., as a defendant. The amount of damages being sought is not specified.

It alleges that Mau-Goffredo used a handgun owned by Carroll to kill Nguyen, who had driven Mau-Goffredo to the parking lot of the scenic lookout on the evening of July 6, 2006.

Mau-Goffredo is also charged with using the same gun to murder married couple Jason and Colleen Takamori, who were in a nearby car in the parking lot.

"This unprovoked triple homicide was an act of infamy," said the suit, filed by attorney Richard Pafundi.

Pafundi would not discuss the suit Thursday.

Last year, suits filed by Lai and Liane Takamori, daughter of the Takamoris, against the mother of Mau-Goffredo were settled out of court.

According to legal papers filed in those suits and a related case, Takamori had initially sought $3.6 million in damages from Mau-Goffredo's mother but later said she would settle for $2.75 million.

Lai originally sought $4.675 million on behalf of herself and her two children.

Terms of the final settlements have been sealed by the court.