Sonoma County District Attorney Jill Ravitch said Thursday that she will not file criminal charges against a 22-year-old Sebastopol man who was involved in a fatal collision with a bicyclist in July.

Adam Bigham was headed to his construction job July 31 when Modesto cyclist Ruben Hernandez struck Bigham's pickup on Fountain Grove Parkway in Santa Rosa.

Hernandez, a 37-year-old teacher who was attending a conference in Santa Rosa, died at the scene from the injuries he suffered in the 7 a.m. crash.

Bigham had turned left in front of Hernandez heading onto Thomas Lake Harris Drive. Witnesses reported his view of Hernandez may have been blocked by another vehicle, Ravitch said.

Hernandez also was reported to be "going a pretty swift speed," she said.

Ravitch said there was insufficient evidence to charge Bigham with misdemeanor manslaughter, which carries a penalty of up to a year in county jail.

Tests revealed that Bigham was not using drugs or alcohol at the time of the crash, Ravitch said.

Hernandez's family could not be reached for comment Thursday. He left behind a wife and 2-year-old daughter.

Ravitch said the deputy prosecutor who reviewed the case contacted the Hernandez family to convey that charges would not be filed.

"He felt they understood the basis for our decision. It's a tragedy," Ravitch said.

David Bush, Bigham's Petaluma attorney, said his client was "really relieved" to not be facing charges.

"We don't want to stress it, but he's a victim in this as well," Bush said.

Hernandez's death marked the fourth fatality at or near the turn onto Thomas Lake Harris Drive going back to 1995. The section of Fountain Grove Parkway where the road intersects is a steep and curving two-lane road that does not include bike lanes.

"This was an accident that was preventable, and should have been prevented," Bush said.