A senior criminal investigator with the Santa Barbara County District Attorney’s Office was killed late Thursday in a collision with a suspected drunken driver on Highway 154, just north of Highway 246 in Santa Ynez. A 22-year-old Santa Barbara woman was arrested in the case, the California Highway Patrol said.

Laura Cleaves, 53, of Santa Ynez, a senior DA’s investigator, was driving her Dodge Stratus westbound on Highway 154 when her vehicle was hit head-on by a Mercedes-Benz just before midnight. According to the CHP, the Mercedes driver, Ashley Johnigan, 22, of Santa Barbara, was arrested and booked on a charge of driving under the influence of alcohol.

CHP officers said they had pulled up behind the Mercedes moments earlier on eastbound Highway 154 near Armour Ranch Road after they received a call that that driver was possibly intoxicated. Officers found the sedan stopped, partially in the eastbound lane of the highway.

As the officers neared the car on foot, Johnigan reportedly sped away, heading east. She allegedly crossed over the dividing double yellow line into the westbound lane and collided head-on with Cleaves’ vehicle. After the crash, CHP officers said, the Mercedes continued down the road and hit a Ford Escape. Johnigan and the driver of the Ford Escape sustained minor injuries.

Highway 154 was closed until about 7:30 a.m. Friday while authorities investigated the scene.

The Coastal Division CHP Multidisciplinary Accident Investigation Team (M.A.I.T.) is handling the collision investigation and the state Attorney General’s Office will be handling the prosecution of the case.

Cleaves’ husband, Steve, is a county sheriff’s sergeant and they have two adult daughters, Krista and Kelly. Memorial plans have not yet been set but a memorial account, the Laura Cleaves Memorial Fund, has been established at Santa Barbara Bank & Trust. Donations can be made at any branch.

Later Friday, a multiple-vehicle collision just west of the San Marcos Pass summit blocked traffic for about 90 minutes while the wreckage could be cleared. Three people were transported to Santa Barbara Cottage Hospital, one with moderate injuries, the others with minor injuries.

The 4 p.m. accident involved a GMC Sonoma pickup, a GMC Yukon, a Honda Accord and a stretch limousine. Alcohol and drugs were not determined to be a factor in the collision.