Driver in crash that killed CHP officer, motorist was on phone, officials say

Matthew Sean Walker, 36, of Rocklin, has been charged with manslaughter in the deaths of CHP Officer Kirk Griess and Jaime Bueza. Matthew Sean Walker, 36, of Rocklin, has been charged with manslaughter in the deaths of CHP Officer Kirk Griess and Jaime Bueza. Photo: Handout Photo: Handout Image 1 of / 9 Caption Close Driver in crash that killed CHP officer, motorist was on phone, officials say 1 / 9 Back to Gallery

The driver charged with striking and killing a California Highway Patrol motorcycle officer and another man at a traffic stop last week on Interstate 80 in Fairfield was on his cell phone and distracted at the time of the crash, the CHP said Wednesday.

Sean Matthew Walker, 38, of Rocklin (Placer County) was arrested and held on two charges of vehicular manslaughter, filed by the Solano County district attorney’s office.

Officers said Walker was behind the wheel of a 3/4-ton Chevy pickup truck when he hit 46-year-old Kirk Griess and 49-year-old Jaime Bueza Manuel on the right shoulder of I-80 near Manuel Campos Parkway on Friday morning.

Griess had pulled over a gray Saturn sport utility vehicle driven by Manuel for an unknown reason when they were struck.

The crash was caused by distracted driving that “was 100 percent preventable,” said Officer Custodio Lopez, a CHP spokesman.

Griess, a 19-year-veteran of the force, leaves behind a wife and three children.

He was “a genuinely good man, great friend, a highly respected CHP motorcycle officer, outstanding United States Marine, a huge fan of Disneyland, and a caring soul committed to helping everyone around him,” the patrol said in a tribute on its website.

Manuel, a Philippine immigrant, is survived by his wife and daughter in the Philippines.

Lopez said Walker was hospitalized after the crash but was released later Friday.

Evan Sernoffsky and Bob Egelko are San Francisco Chronicle staff writers. Email: esernoffsky@sfchronicle.com, begelko@sfchronicle.com Twitter: @EvanSernoffsky @Egelko