A crash that killed a 47-year-old bicyclist from Los Altos Hills last month was caused by an unsafe turn she made as she headed down Alpine Road alongside a 26-wheel truck, according to the California Highway Patrol.

The Nov. 4 collision with the big rig claimed the life of Lauren Ward, a mother of two and an active community member who friends and family have described as an avid bicyclist. The crash was the third fatal collision for the big rig’s driver, Gabriel Manzur Vera.

In each of the crashes, Vera was determined not to be at fault.

According to a redacted CHP report released Monday night, Vera was driving his truck west on Alpine Road in the right lane between 10 and 15 mph at about 3:40 p.m. and Ward was to the immediate left of the vehicle sharing the lane. Ward, who was riding at an unknown speed, “unsafely turned” her Trek bicycle and fell to her right side, the report states.

The big rig continued and its tires struck Ward, who was pronounced dead at the scene.

The 33-page report shows that Ward caused the crash by making the turn, said CHP spokesman Art Montiel, but investigators were unable to determine why she turned.

“We know it was caused by an unsafe turn,” he said. “We don’t know and we may never know what actually caused her to make that unsafe turn.”

The report included a summary of the investigation and statements Vera made to authorities.

The trucker told the CHP the collision happened as he was moving from the right westbound lane into a lane that turned right onto southbound Interstate Highway 280. Vera told the CHP he had his right blinker on and was looking at his right rear view mirror, but when he looked forward he heard a “bump.”

Vera realized he had collided with Ward, pulled over and called 911.

He told the CHP he thought another vehicle passed his truck on the left shortly after he pulled away from the stop sign at the northbound Highway 280 on-ramp. But he couldn’t recall how much time passed between the point the vehicle drove past and when he felt the bump.

Montiel said investigators never found any eye witnesses to the crash and couldn’t rule out the possibility that another vehicle may have been indirectly involved in the collision.

The redacted report didn’t include sections titled “cause” and “recommendations,” which Montiel said were withheld for legal reasons.

However, the investigation shows that Vera was not at fault, he said.

“We can conclude there was nothing that the truck driver did that caused her to fall into the pathway of the moving truck,” Montiel said.

Vera was also involved in a fatal crash in 2007 in Santa Cruz. In that collision, his 26-wheel truck struck a popular Pacific Collegiate School teacher named John Myslin at the intersection of Mission and Bay streets. Vera was making a right turn when Myslin tried to pass him on the right.

Police determined Vera wasn’t at fault in that crash.

Myslin’s parents, however, sued and in March, Vera and Randazzo Enterprises settled the wrongful death suit for $1.5 million.

Vera’s first fatal crash happened Dec. 31, 2003, on Highway 1 in Monterey County, according to CHP records. He was driving on Highway 1 through Moss Landing when another vehicle driven by Annette McDaniel, 53, reportedly crossed into oncoming lanes and struck his truck head-on. The Monterey County Coroner’s Office reported at the time McDaniel had been weaving in and out of her lane and crossed the center line before colliding with the 26-wheeler. She was killed in the crash.

Ward’s family has hired an attorney, John Feder, to conduct a separate investigation into the latest crash. Prior to the release of the CHP report Monday, Feder said he believed the agency’s Multidisciplinary Accident Investigations Teams was also possibly investigating the collision.

Ward’s husband, Bob, declined to speak with a reporter when reached by phone Monday.

E-mail Jesse Dungan at jdungan@dailynewsgroup.com.