Debbie Franzman, 50, of Nipomo, died Tuesday shortly after she was attacked by what is being described as a 15- to 18-foot-long great white shark. According to wire service reports, she was swimming about 75 yards off of Avila Beach at the time she was attacked.

"This is just so horrible," Chico State Professor Kathy Kaiser said Wednesday afternoon. "I was her mentor. I was her adviser."

Franzman had been a San Francisco Bay Area resident before coming to Chico State in the early 1970s, according to Kaiser.

"One of the first things she did was get involved with CAVE," recalled the sociology professor. CAVE (Community Action Volunteers in Education) is a campus group that provides volunteers to a range of service groups and charitable organizations.

Kaiser said Franzman organized some of the first volunteer trips among Chico State students to the state mental hospital in Napa and to the veterans home in Yountville.

"She served a full internship for a semester at Napa, at the state mental hospital for children," said Kaiser.

Franzman received her master's degree in sociology in the spring of 1977.

Kaiser still has a copy of Franzman's master thesis, which was a study of child-rearing approaches between 1850 and the 1970s.

Franzman had always been athletic, and at one point was a champion racquetball competitor, according to Kaiser.

She also got into triathlons, which are a combination of swimming, bicycling and running.

"Swimming got to be more of an interest for her when she got into triathlons," said Kaiser.

After graduating from Chico State, Franzman went to work first at Lassen Community College in Susanville, and later for Allan Hancock Community College in Santa Maria.

A preliminary autopsy conducted Wednesday on Franzman reportedly supports the idea that she was attacked by a great white shark.

Witnesses to the deadly attack reported seeing a large fin as Franzman screamed for help.

Lifeguards pulled her to shore, where she died. Bite marks on her legs were consistent with those seen in previous attacks by great white sharks, San Luis Obispo County sheriff's Lt. Martin Basti said.

Shark expert Robert Lea, present during the autopsy, estimated the fish was between 15 and 18 feet long.

"That's incredibly large," Basti said.

An unknown species of shark was spotted in the area after the attack, Basti said.

Franzman likely bled to death after her left femoral artery was severed in the attack, Basti said.

Franzman's death marked the 10th fatal shark attack in California since 1952 and the first death since 1994, according to state Department of Fish and Game records.

She swam in the area by the Avila Beach Pier several times a week, friend Andrea Sanders said through tears.

"She loved it. She would talk about how fun it was to swim and play with the seals," Sanders said.

Franzman was wearing a full wetsuit and swim fins when she was attacked, Lea said. The state marine biologist said the shark may have mistaken Franzman, silhouetted against the surface, for a seal. The sharks are ambush predators and attack their prey from below.

Avila Beach, located about 200 miles northwest of Los Angeles, was closed to swimmers after the attack.

Great white sharks are a protected species in California.