A prosecutor told jurors today that a Castro Valley man should be convicted of murder for fatally stabbing the mother of his children in front of her workplace three years ago after she broke off their 20-year relationship.

In her opening statement in Luis Hernandez's trial, prosecutor Lindsay Walsh said Hernandez was "desperate" to get back 46-year-old Rose Goulart, the mother of his two teenage children, after she finally gained the courage to move away from him after suffering years of abuse.

Goulart tried to keep her new address and her new phone number a secret from Hernandez, 49, but he eventually tracked her down because "he wanted to show her that he was still in control and she couldn't get away no matter what she did," Walsh said.

Goulart sought and obtained a partial restraining order against him but he still had the right to see her occasionally as long as he didn't annoy or harass her, the prosecutor said.

According to Walsh, Goulart kept detailed notes of Hernandez's threats against her and on May 28, 2009, she told her attorney in an email that, "I'm really scared and I really fear for my life now."

Hernandez killed her the next morning, Walsh said.

Hernandez knew that Goulart's colleagues at her job at the Bay Valley Medical Group in Hayward, which is adjacent to St. Rose Hospital, would recognize him if he drove there in his own car, which is distinct and loud, so he borrowed his aunt's car so he could ambush her and waited in the parking lot for her, Walsh said.

She said that when Goulart drove to her job on the morning of May 29, 2009, Hernandez blocked her car with his aunt's car in the parking lot and after she got out of her car he stabbed her repeatedly with a screwdriver he had fashioned into an ice pick.

Several of Goulart's work colleagues tried to stop Hernandez but he kept stabbing her because "he wanted to complete the task he'd come to do," Walsh said.

Witnesses told police that Hernandez manipulated and twisted the screwdriver in Goulart's chest and then he left her on the ground with the tool sticking out from her chest and kicked her twice in the head, Walsh said.

Goulart was pronounced dead at a nearby hospital and police arrested Hernandez at the scene.

The killing was so brutal that the Alameda County District

Attorney's Office originally sought the death penalty for Hernandez but it later decided to seek life in prison without the possibility of parole instead.

Walsh, who declined to comment on that decision, asked jurors to convict Hernandez of murder and stalking and the special circumstance of lying in wait.

Hernandez's lawyer, Deborah Levy, admitted to jurors that he killed Goulart, saying, "We're not going to deny the act, we're not denying the actions."

But in a possible bid to ask jurors to convict Hernandez of the lesser charge of voluntary manslaughter instead of murder, Levy said his state of mind at the time is important and she believes he "snapped" and acted "in the heat of passion and rage."

Hernandez was drinking and took a lot of drugs before the fatal stabbing and wasn't thinking clearly, Levy said.

"If you plan to kill someone you don't do it in front of a lot of witnesses," she said.