Prison internal affairs investigators are trying to determine why an inmate who was shot and killed during an escape attempt in downtown Hilo apparently was not wearing all of the restraints required during prisoner transports, including a waist chain, leg shackles and handcuffs.

Frank Lopez, acting director of the state Department of Public Safety, said he has not confirmed reports that a restraint key was found in the street next to the prison van after inmate Thane K. Leialoha was shot Tuesday on Haili Street near a busy intersection.

"If he had a key, that would be troubling as to how he got it," Lopez said.

Corrections staff reported that Leialoha, 28, was wearing restraints as required by department procedure when he left Hilo District Court to return to the Hawai'i Community Correctional Center just before the escape attempt, Lopez said.

Inmates are supposed to be transported in vans that lock from the outside, and prison officials will try to determine how Leialoha left the van at the intersection of Haili and Kilauea Avenue at about 2:07 p.m. Tuesday.

Sabrina Kauai, Leialoha's girlfriend, said a witness told her Leialoha shoved the corrections officer to the ground before fleeing down Haili Street in a brown prison jumpsuit. Kauai said the witness reported that the officer fired from a sitting position and struck Leialoha in the back of the head.

Lopez said he has heard conflicting accounts of how Leialoha was restrained. Some witnesses said he wore no restraints when he escaped from the van, while at least one witness said Leialoha was handcuffed.