The California Highway Patrol on Monday identified the driver in last week's fatal Phoenix Lake Road crash as Janiece Behymer.
Behymer, 57, of Sonora, was driving west on Phoenix Lake Road in a 2005 Nissan Frontier when she collided with a tree about 12:30 p.m. Friday, between Sommette and Midland drives.
It was unknown why her truck veered off the road and struck the tree. The cause is under investigation, including looking into a possible medical complication, according to CHP.
She wasn't wearing a seatbelt at the time, CHP said.
Behymer, formerly Janiece Ross - her name had not yet been changed on her driver's license - had lived in Sonora since 1987. She married family physician Dr. Richard Behymer in 2007.
She worked for years as a medical office manager in Sonora until she brought her mother, Joy Vint, to Sonora. She left her job to care for Vint.
Her daughters, Julie Wilson and Stephanie George, also live in Sonora.
Behymer's husband described her as a devoted grandmother and wonderful wife. He said she was also passionate about water safety and kids.
She taught swimming for many years to young children. Many of her swimmers were the children of prior students, Behymer said.
She was born and raised in San Diego and spent most of her life there. She raised her oldest daughter, was a certified lifeguard and maintained a pool there.
She also used to surf, Behymer said.