Timothy Arie Kooyman, 26, was convicted last month in Riverside Superior Court of three counts of animal cruelty for mutilating and killing cats in 2008 at a motel in Corona.
Prosecutors said Kooyman decapitated a cat with an ax, killed another by repeatedly slicing it with a razor and ran over another with his truck. He also broke each of the cats' legs before killing them.
Kooyman is serving a five-year prison term for committing similar acts against cats in Rancho Cucamonga. That sentence was lengthened to seven years and eight months Friday by a judge at Larson Justice Center in Indio.
"It's a concern to me what he does in the future," said Judge John M. Davis, who called Kooyman's crimes against cats "mind-boggling."
Kooyman's latest convictions include a second and third strike as part of California's three-strikes law. If he is convicted of another felony, he could be sentenced to 25 years to life in prison.
Kooyman, clad in orange jail scrubs, did not make a statement during his sentencing. He said only "No, sir" and "Yes, sir," when instructed of his appeal rights.
During a two-week stay in April 2008 at the National Inn Motel in Corona, Kooyman lured cats from a nearby neighborhood and took them back to his room, prosecutors said.
Four animal activists spoke in court before Kooyman was sentenced. They mainly addressed their comments to the judge, but some at times spoke directly to Kooyman.
Leroy Moyer, the founder and president of Voices For Pets, said he has no hope or sympathy for Kooyman, who in interviews with investigators complained of a difficult upbringing.
"I just can't understand why you did what you did," Moyer said.
Lori Curran, who spoke on behalf of Animal Rescue Foundation, said she is a sergeant with 20 years of experience at the Richmond Police Department.
She said she has investigated murder cases where those responsible committed previous violent acts against animals.
"The behavioral patterns leading up to the homicide are eerily similar," she said.
She said that in her work, she has seen "the worst of the worst," and she ranked Kooyman among the top three worst people she has encountered.
"You are a coward and you deserve to rot in hell," Curran said.
Kooyman's defense attorney, Souley Diallo, said in his comments to the judge that Kooyman's acts were horrific. But he encouraged the judge to consider other issues besides Kooyman's acts, such as Kooyman's mental health.
"He's a person who obviously needs help," Diallo said. "He's acknowledged that."
Deputy District Attorney Sharunne Foster asked Davis to extend Kooyman's sentence by three years and eight months.
"I think Mr. Kooyman is beyond rehabilitation," she said.
After the hearing, Foster said her request was an "uphill battle" because the sentence would have required an unusual interpretation by the judge of Kooyman's previous animal-abuse case in Rancho Cucamonga.