CUPERTINO, Calif. -- The lawyer for a Santa Clara County sheriff's deputy who struck and killed two bicyclists says fatigue may have played a prominent role in the crash.

Mary Sansen said 27-year-old James Council doesn't know exactly what happened when his squad car veered into the path of a group of cyclists on a winding Cupertino road.

According to the attorney, Council had worked a 12 1/2-hour shift the day before the crash and believed fatigue may have been an issue.

"A 12 1/2-hour shift is brutal," Sansen said. "You're not sitting behind a desk. Even if you don't work in a high-crime area, you're always on alert for 12 1/2 hours. It is exhausting."

Sansen said she also has advised Council not to speak to investigators.

"You want the truth on the record," she told the San Francisco Chronicle. "What you don't want is someone having an emotional meltdown. There are cases where for days or weeks I don't allow a client to give a statement because they're not in an emotional state to give a coherent statement."

Council was on routine patrol going northbound on winding Steven's Canyon Road when he swerved across the double-yellow center dividing line into a southbound group of cyclists. The deputy immediately began CPR on one of the fallen cyclists and called for help.

Matt Peterson, 29, of San Francisco was killed, 30-year old Kristy Gough was severely injured and died at the hospital, while a third rider was also injured but has been released from the Stanford Medical Center.

The sheriff's department declined to speculate on a possible cause or discuss statements reportedly from witnesses who claim they overheard Deputy Council say he fell asleep at the wheel. Two separate witnesses who were on the scene immediately after the accident reportedly claimed that the distraught Council said that he had dozed off while driving.

"I haven't spoken to him about the incident. I've just spoken with him about his condition. He's devastated. He's a great young man, so he's gonna wear this for a long time," said Sheriff's spokesman Sgt. Don Morrissey.

On Monday, people who knew both riders killed in the accident spoke of their shock and disbelief at losing two active members of the Bay Area's cycling community.

Peterson was a member of San Francisco's Roaring Mouse Cycle Racing Team. Fellow teammates were shattered by the loss of their friend.

"I realized last night what I wanted to do was call him and say 'What's going on?’ because I usually talk to him every single weekend," said Roaring Mouse team spokesman Dave Parrish. "There were just so many moments when I was ready to send him a text message and I realized he's not going to be there to pick up my message."

A memorial service for Peterson was scheduled for 7 p.m. Thursday night in San Francisco.