Big Island police are asking for the public's help in identifying a motorist who sexually assaulted a hitchhiker over the weekend.

The man was traveling toward Puna on Route 11 near the Kea'au Ball Park Saturday night between 10:30 and 11:30 p.m. when he picked up a woman who was hitchhiking alone.

The driver turned off the highway onto a dirt road in the Kurtistown area, where he sexually assaulted the victim, police were told.

The motorist is a heavy-set local male in his 30's, is between 5 feet 7 and 5 feet 10, and weighs between 200 and 280 pounds.

He has very short dark hair, dark skin, hazel eyes and a thick mustache. The truck is an older-model, faded pinkish-gray full-size four-wheel-drive pickup with large tires.

Anyone with information about the case is asked to call Officer BJ Duarte at 808-961-2373 or the police nonemergency line at 808-935-3311. Tipsters who prefer to remain anonymous may call CrimeStoppers at 808-961-8300 in Hilo or 808-329-8181 in Kona.

Police caution people not to hitchhike or accept a ride from anyone they don't know.