The mother of the man convicted of murdering East Palo Alto police Officer Richard May told jurors during the penalty phase of her son’s trial today that his life is still valuable.The penalty phase will determine whether Alberto Alvarez, 26, will be sentenced to death for fatally shooting May on Jan. 7, 2006. He was convicted Nov. 25 of first-degree murder with the special circumstance of killing a peace officer after jurors deliberated for just under six hours.Alvarez’s defense attorneys have asked that jurors choose the lesser sentence of life in prison without the possibility of parole.Speaking through a Spanish interpreter, Alvarez’s mother, Autelia Alvarez, testified this morning that even though her son didn’t do well in school, he helped her with his sisters when her husband was in jail or out drinking.When Alberto Alvarez was 3 months old, his father, Leo Alvarez, went to prison for selling drugs, his mother said.She said he returned home after about three years and got work as a janitor. However, in 1991, he started drinking heavily after his mother passed away, she said.”He disappeared for up to a week at a time,” she said of her husband.She said she worked full time then to support their family, and has worked ever since she moved to the U.S. from Mexico in the 1970s. During her husband’s drinking phase, she said, there was one incident of domestic violence in which he slapped her.She said that her husband had never hit Alvarez or his two daughters.Prosecutor Steve Wagstaffe asked her if she had been a good mother to Alvarez.”You did everything you could?” Wagstaffe said.”Yes,” she answered quietly.Alvarez started crying when his mother, through her own tears, said she had visited her son twice a week at the Maguire Correctional Facility in Redwood City after his arrest on Jan. 8, 2006, for May’s murder, and that he always asked about his two younger sisters.”He’s been convicted of murder,” Alvarez’s defense attorney Eric Liberman said to Autelia Alvarez. “But has he been a good son to you?”Yes,” she said.”Has he been a good brother to his sisters?” Liberman asked.”He’s been a very good brother,” she said.”Did he help you when your husband was gone?” Liberman said. “Yes,” she answered.Pictures of Alvarez as a child, including one of him with his sisters and parents, were shown to the jurors.The emotional testimony followed two days of statements from May’s family and friends, who told jurors that his absence has left many of them feeling sad and alone.May’s wife, three daughters, mother, stepfather and sisters each told stories they remembered of May and showed pictures from his life.The defense is expected to present testimony through Tuesday, followed by closing arguments in the penalty phase.