Marco Topete's father told jurors Tuesday that he drank heavily when his son was young, beat the boy with a belt and took him along on drug deals.
Later, after both had served stints behind bars, Manuel Topete said, he invited his son to join him selling methamphetamine.
The elder Topete took the stand in Yolo Superior Court during the penalty phase of his son's murder trial to try to persuade jurors to spare him from execution.
The same jurors convicted Marco Topete, 39, earlier this month of gunning down sheriff's Deputy Jose Antonio Diaz in June 2008 following a high-speed chase near Dunnigan.
"I felt guilty about what had happened," Manuel Topete testified, after his son's lawyer, Dwight Samuel, asked him why he had come forward.
Manuel Topete, 61, of Arbuckle gray haired and wearing jeans and a windbreaker hung his head as he testified. A Spanish translator assisted in the Woodland courtroom.
Defense lawyers have presented evidence of Marco Topete's troubled childhood to try to persuade jurors to recommend a sentence of life in prison without the possibility of parole.
Manuel Topete testified that, when his son was young, he would often drink so much beer after work that he threw up in the morning. When he started working the night shift, Marco woke him during the day.
"I would grab him and hit him with a belt," Manuel Topete said. The beatings happened several times a week, he said.
Other times the boy would annoy him while he was working in the garage and drinking beer, he said. He would swear at him and hit him, he said.
Starting when Marco was 8 or 9, Manuel Topete said he started selling marijuana. He frequently took his son along on drug deals, he said. "He didn't know, but he would go with me," he told jurors.
Manuel Topete said he was eventually arrested in Mexico and spent five years in prison there when his son was a teenager. When he came home to Yolo County, Marco had been in trouble with the law and was locked up, he said.
The elder Topete said he started selling "crank" and invited Marco to join him when he was released. Marco agreed, he said.
Marco Topete was convicted of a 1997 shooting at a Woodland convenience store. When he got out of Pelican Bay State Prison in 2007, he was a "different person," who was good to his wife and baby daughter, his father said.
Samuel asked Manuel Topete what he would miss if his son were executed.
"The love I have for him, and the love I for my grandchild," he answered.