A 23-year-old man accused of the execution-style slaying of three people at Tantalus could spend the rest of his life behind bars if convicted on 18 felony charges arising from the shootings and a home invasion robbery.

Adam Mau-Goffredo was indicted yesterday by the O'ahu grand jury in the killing of a taxi driver and a couple at a Tantalus lookout, and the home invasion robbery of three people at a Round Top Drive home Thursday night.

The charges include first-degree and second-degree murder, armed robbery, firearm and theft charges.

Because he is accused of using a semi-automatic gun in the killings, he could get a sentence that would put him in prison for at least 60 years without any chance of parole.

Mau-Goffredo, who had been diagnosed as a paranoid schizophrenic and had been living with caretaker William R. Carroll Jr. at Carroll's Palolo residence, is accused of stealing a gun from the caretaker Thursday.

He then allegedly used that weapon to kill taxi driver Manh Nguyen, 50, and Jason and Colleen Takamori, both 53.

Mau-Goffredo also is accused of using a gun to threaten the victims in the home invasion robbery.

He was arrested later that night on Tantalus Drive in a Jaguar taken from the Round Top Drive residence, according to police. Police said they recovered a loaded pistol magazine from his left front pocket of his pants. They also said they recovered a gun from the car.

Mau-Goffredo was being held on $25 million bail, but Circuit Judge Derrick Chan granted a request by City Prosecutor Peter Carlisle to hold Mau-Goffredo without bail pending a hearing on whether bail should be issued.

Carlisle said the indictment involves a "mass murder."

"It appears to be done in execution style with shots to the head," he told the judge.

The autopsy results were that Jason Takamori was shot twice in the head, and his wife and Nguyen were each shot once in the head.

Carlisle later would not elaborate on what other evidence supports the contention that the shootings were execution-style.

Mau-Goffredo's attorney, Brook Hart, said he was not surprised by the indictment, which canceled a preliminary hearing in the afternoon.

"If the evidence shows that the people were shot in the head, that's what the evidence will show," he said. "I prefer to address the evidence when we get to court, and not characterize it."

Hart said the bail issue will be addressed later, but that he considers it a secondary point to other issues in the case.

"No bail is not much different from $25 million bail," he said.

He said his client is no longer on routine suicide watch. Mau-Goffredo was initially under suicide watch, but is now at the O'ahu Community Correctional Center's male acute mental health module, said Louise Kim McCoy, communications director for the state Department of Public Safety.

Hart said until he has a chance to spend some "extended time" with Mau-Goffredo to determine "what's going on with him," he won't say what they will do next.

He said they can't say what plea his client will enter to the charges until they first determine whether he's competent to render a plea.

The date for the arraignment and the hearing on the prosecution's no-bail request have not been set, but are expected to be held sometime next week.

Mau-Goffredo was indicted on a charge of first-degree murder of killing more than one person, and three counts of second-degree murder, one for each slaying victim.

The first-degree murder charge carries a mandatory sentence of life without parole. But under state law, the governor can commute the sentence to life with parole after 20 years. It would then be up to paroling officials to release him on parole on that charge.

But because Mau-Goffredo is charged with using a semi-automatic gun to murder the victims, if he is convicted, he could be sentenced under state law to at least 60 years in prison without the possibility of parole, which would mean he could not be paroled earlier.

The indictment was returned after a confidential grand jury session. Among the witnesses were Carroll and former U.S. Magistrate Judge Joseph Gedan, a victim in the Round Top Drive home invasion.

Reach Ken Kobayashi at kkobayashi@honoluluadvertiser.com.