By Raiza Giorgi,

Family members and friends are remembering Sienna Diaz-Tremper as “a loving soul who aimed to serve everybody around her, no matter who they were,” said her mother, Genevieve Tremper.

Helping others and taking care of family and friends was very important to her daughter, she added.

“This is a nightmare. I’m so broken,” Tremper said.

Diaz-Tremper, 21, was killed, and her passenger Chelsee L. Fuerch, 22, of Santa Maria was critically injured in a rollover crash June 18 on Figueroa Mountain Road, according to the California Highway Patrol. 

The tragedy occurred about 5:30 p.m. in the 4100 block of Figueroa Mountain Road near the Chamberlin Ranch in Los Olivos, after Diaz-Tremper “made an unsafe turning movement” in her 1998 Toyota Corolla as she was traveling northbound, according to Officer Kevin McCool, public information officer for the CHP. 

Fuerch was flown by Calstar medical helicopter to Santa Barbara Cottage Hospital for treatment of major injuries, the CHP said. Both women were wearing their seatbelts at the time of the crash, which remained under investigation, McCool added.  

A GoFundMe account has set up for Fuerch, who suffered spinal cord injuries in the accident, according to the Caring Bridge website (

“Although we don’t know details yet or a prognosis, it is clear that Chelsee will need lots of time to heal,” wrote Christy Reasner, one of her cousins.

Fuerch graduated from CSU Channel Islands in May with a bachelor of science in psychology.

Diaz-Tremper was born in Nipomo and later moved to Orcutt, attending Alice Shaw Elementary and Lakeview Junior High. She played softball and was a cheerleader at Righetti High School, and very active in 4-H and Future Farmers of America.

“We moved to Figueroa Mountain at the end of her freshman year, a different life for us. We worked hard on the ranch every day, all the kids included. Ranch work is  required for everyone in the family. We don’t have employees,” her mother said.

Diaz-Tremper’s favorite spot was at the front door looking at the sunset each day, her mother recalled.

She then attended Santa Ynez Valley Union High School and was a member of the varsity softball team and FFA, raising market pigs. She went back to Righetti to finish her schooling and had plans to join the Army when a friend died and left a toddler behind.

“Sienna moved in with the family to raise the baby until she was ready to spread her wings. She then moved to Montana with family in late 2015 to caretake for her uncle and pursue a career in nursing and emergency services,” Tremper said.

When Diaz-Tremper returned for a wedding, she decided to stay in the valley and worked at the Bear and Star in Los Olivos. When she died, she was working at the Los Olivos Grocery store and Kaena tasting room.

“Sienna contributed beyond measures, and I can’t begin to say what an impact she had on her four sisters, brother, her dad and I,” her mother added.