Sonoma County jurors convicted a 28-year-old Windsor man Monday of felony vehicular manslaughter in a fiery Highway 101 crash that killed five family members.

On the third day of deliberations, jurors found Ryan Karr guilty of five counts of felony vehicular manslaughter without gross negligence while intoxicated, rejecting alternate misdemeanor charges that could have allowed him to avoid state prison.

Although Karr hadn't been drinking and it was unclear if he was impaired, jurors said they were swayed in part by toxicology reports that showed he had trace amounts of marijuana in his system.

"It was a hard decision but I think it was the right one," said juror Richena Johnson of Santa Rosa.

Karr had been free but was remanded into custody with the verdict. His eyes welled with tears as bailiffs put him in handcuffs over objections from his lawyer, Andy Martinez, and prepared to escort him to jail.

Judge Rene Chouteau said jail was right given the felony convictions. Karr will be sentenced Feb. 18., when he faces a maximum of six years and eight months in prison.

"Once again it's a reminder of the lethal combination of using drugs and driving in a reckless manner," District Attorney Stephan Passalacqua said. "It's sad this individual deliberately used drugs and chose to drive and in the process destroyed an entire family."

Karr pleaded no contest late last month to a misdemeanor charge of "having recently used cocaine" prior to the crash, his attorney said, but that charge and pleading was not revealed to the jury prior to its verdict.

Prosecutors alleged Karr was driving too fast in rush hour traffic Jan. 19, 2007 when he rear-ended a stopped Honda Civic, which burst into flames, killing Windsor residents Maria Lopez Camacho, 54; Edith Carlos Medina, 23, her son, Fernando Carlos, 7; Almadelia Mendera-Basurto, 16; and Carmina Solorio, 23, of Mexico.

Medina's other son, then-4-year-old Christian Flores Carlos, survived with serious burns, but lost an arm and leg.

Karr did poorly on a field sobriety test and a blood test taken at the scene showed he had trace amounts of cocaine and marijuana in his system.

His attorney argued he was not impaired and his behavior at the accident scene could have been influenced by shock. Criminal charges were not filed until almost a year after the crash.

As part of the jury's findings, Karr was convicted of speeding but cleared of charges he was driving too closely.

"I think there is enough evidence to overturn the verdict," said Martinez, who vowed to appeal.

Opening arguments came Nov. 30. The jury began deliberations Dec. 22 and was off last week.

Jurors asked to have testimony read back from at least two toxicologists and struggled over how to interpret a report that showed Karr had 2.5 nanograms of THC from marijuana in his blood. Martinez said unlike alcohol intoxication, there is no legal standard for marijuana impairment.

"They didn't know what that number meant," Martinez said.

Juror Jennie Giles of Santa Rosa said she wasn't convinced Karr was guilty of felony charges but changed her mind under pressure from others.

"I feel sorry for him," Giles said. "His demeanor in the courtroom was respectful. I feel like it was an accident."

Other jurors said the CHP botched the investigation by allowing their lead officer to go on stress leave in the midst of the case.