A 37-year-old man being held at a Mainland federal medical facility after his insanity acquittal in the 1999 fatal shooting of a Big Island park ranger should spend the rest of his life in custody there, a federal prosecutor said yesterday.

U.S. District Judge Susan Oki Mollway yesterday ruled that Eugene Frederick Boyce III is dangerous and ordered him to a secured medical facility to be chosen by the federal Bureau of Prisons.

Assistant U.S. Attorney Ken Sorenson, who argued that Boyce should not be released, said the former Big Island resident will remain in custody until he demonstrates that he is not a danger.

"The government believes quite firmly that his mental disease renders him a substantial danger, and we'll be fighting to keep him in custody for as long as we possibly can," preferably the rest of his life, Sorenson said.

Boyce was charged with first-degree murder in the death of U.S. Park Service ranger Steve Makuakane-Jarrell, 47, at Kaloko-Honokohau National Historic Park in December 1999. Makuakane-Jarrell is the only federal park ranger murdered in the Islands.

Makuakane-Jarrell was shot after responding to a complaint about Boyce's dogs. Boyce, who was homeless at the time, grabbed the ranger's gun during a struggle and shot him, according to court records.

Boyce's case was delayed several times because he was not ruled competent to face trial until this year. At the trial, mental-health experts testified Boyce suffered from severe paranoia and schizophrenia.

Last month, Mollway returned the insanity acquittal, setting up yesterday's hearing.

Les Inafuku, chief ranger at the Kaloko-Honokohau park, said rangers were pleased because in view of the judge's earlier ruling, her decision yesterday was "the best outcome we could hope for."

"We have to look at the big picture and not just think of park rangers," he said. "If somebody is a danger to a park ranger, obviously that person is probably a danger to everybody."

Reach Ken Kobayashi at kkobayashi@honoluluadvertiser.com.