HONOLULU -- Prosecutors on Kauai have opened a homicide investigation into the tour helicopter crash there in September that killed three people.

The pilot of the chopper, who survived the crash, is the target of the homicide probe, which has never been conducted before in Hawaii for a fatal air crash.

When the Heli-USA tour helicopter crashed into the ocean off Kauai's North Shore on Sept. 23, the pilot and five passengers survived the crash, but three of the passengers died in the aftermath.

Now, Kauai prosecutors have opened a homicide probe, looking at possible negligent homicide or manslaughter charges against the pilot, Glen Lampton.

"The FAA (Federal Aviation Administration) has asked us to investigate the matter involving possible homicides," Kauai deputy prosecutor Richard Minatoya said. "Their request is based on concerns for air safety involving helicopter tours on the island."

The FAA's legal department spoke to the Kauai prosecutor's office.

"If they chose to prosecute, then we would very likely be able to make available evidence that we collected in our investigation," FAA spokesman Donn Walker told KITV from Los Angeles.

Lampton, 43, had been flying helicopters on Kauai for about six or seven weeks. He had previously piloted helicopters for a TV station in Louisville, Ky., and for the Houston Police Department. He was not available for comment, and the tour company did not return KITV's phone calls.

"We've been interviewing other pilots and looking into the weather situation -- obviously, involving the decision by the pilot to fly into the weather," Minatoya said.

Other pilots said Lampton should have never flown into a severe thunderstorm. Lampton claimed he maneuvered into the bad storm to avoid colliding with another helicopter.

His passengers contradicted him, saying they never got close to the other chopper.

Mary Soucy, 62, and Catherine Baron, 68, from Portland, Maine, died in the crash with Laverne Clifton, 68, from Beloit, Wis.

Criminal investigations in air crashes are very rare. The only known criminal prosecution in an aviation disaster happened after a Valujet aircraft crashed into the Florida Everglades in 1996 and killed 110 people.

Prosecutors went after a company called Sabretech, which processed oxygen containers investigators believe caused the fire that led to that crash.