The guilty pleas to two counts of manslaughter by Vernon E. Costa, 42, were part of a plea agreement that required prosecutors to drop more serious charges of first-degree murder, two counts of second-degree murder and attempted second-degree murder.

Conviction on any of those original charges would have required that Costa receive a sentence of life in prison.

Pua Lei Santa-Isabel, 26, and Casey Ann Swain, 35, were killed July 16, 2006, when the car they were in ran off a Big Island highway in Kona.

Police alleged Costa used a pickup truck to run the car off the road because it was also carrying his former girlfriend, Janelle Nardin, who survived the crash.

However, Costa defense lawyer Robert Kim said the crash was an accident, and Costa never intended to kill the women.

Kim said an accident reconstruction showed Costa had run off the road during the chase, and was trying to return to the highway when the two vehicles collided, causing the deaths of Swain and Santa-Isabel.

Kim said after the crash Costa also flagged down another car and took Nardin to the hospital, which demonstrated he never intended to kill her.

Costa also pleaded guilty to two counts of leaving the scene of an accident involving serious bodily injury; one count of second-degree assault for injuries suffered by Nardin in the crash; one count of first-degree criminal property damage; and to possession of drug paraphernalia.