A Milpitas man with a long history of violence was sentenced Friday to more than 25 years in prison for beating his former girlfriend’s cocker spaniel to death with a hammer, a third strike for Alex Castro.

Castro, 48, begged the court for mercy, saying such a long sentence was too much for killing a dog, but the judge said he could not ignore the violence Castro inflicted in his life, according to the prosecutor.

“I am appreciative that not only did a jury take this case incredibly seriously, as evidenced by their verdict, but also that the judge did,” said Deputy District Attorney Kevin Smith. “Despite the defendant’s claims he was getting too much time for ‘only killing a dog,’ he is getting this sentence for the violence in his past.”

Castro, a drywall worker, was sentenced to 25 years to life. Because of enhancements to his sentence, the earliest he’d be eligible for parole is 33 years, Smith said.

In an interview for a probation report prepared for the judge, Castro said he believed the most time he should receive for killing Copper in July 2007 was three years, the maximum allowed for felony animal cruelty.

Copper’s owner said she was “satisfied” by the verdict.

“The way he did it was horrible,” said Joanie Gonzalez, of San Jose, who had owned Copper since he was a puppy. “There was no reason for it; that dog didn’t do anything wrong.”

Castro’s attorney did not return phone calls Friday.

During his trial, Castro denied killing the 10-year-old dog, asserting the small pools of Copper’s blood found by investigators stemmed from him moving the dog several times after finding the dog dead near the trailer he shared with Gonzalez at the Main Street Mobile Home and RV park in Milpitas, next to the Ooh La Lodge. Castro said he couldn’t decide how to tell Gonzalez her dog was dead, likely hit by a car, and didn’t want to see her cry.

Prosecutors successfully sought to have Copper’s murder counted as a third strike for Castro because he had two previous violent felonies. In his probation interview, Castro said his first two strikes “are old” and he is not a habitual criminal.

In 1994, Castro and a friend went to pick up a refrigerator at his estranged wife’s house and got into a fight with her then-current boyfriend. The two entered without knocking and teamed up for the fight, with his friend standing on the boyfriend’s legs while Castro choked him. Castro choked the man until he turned blue and finally stopped when his friend said “Alex, he’s almost dead, he’s blue,” according to the probation report.

In 1982, Castro and his father had been at a bar when Castro grabbed a tire iron from his truck and struck two men his father had been fighting with multiple times.

In addition to the two felony batteries with serious bodily injury and assault with a deadly weapon other than a firearm, Castro had 20 misdemeanor convictions, including driving under the influence and driving with a suspended license.

Castro is due back in court Monday for the setting of a trial on charges of soliciting to prevent a witness from testifying in the trial over Copper’s death. While in county jail, he managed to have a letter sent to a Milpitas motorcycle club, asking that a key witness in the case, a member of the club, not be allowed to testify in court, testimony that would have included his statements to a friend about killing Copper. That member did testify.

Gonzalez said she was initially torn that Castro was facing such a long sentence. She had just lost her mother, then her dog — and her boyfriend.

“I really didn’t think that life was the right sentence for killing an animal,” she said. “But as someone said, who knows, it could have a been a child the next time.”

Contact Linda Goldston at 408-920-5862.