The mother of convicted mass killer Kevin Cooper broke into sobs Monday as she pleaded with jurors to spare the life of her son, found guilty in San Diego Superior Court last week of murdering four people in a Chino Hills home in June, 1983. "Just please have mercy on my child. That's all I'm asking. Save my child's life, please," Esther Cooper begged the jurors, moving at least one to tears. The seven women and five men on the jury must recommend a sentence of life in prison without parole or death in the gas chamber for Cooper. After closing arguments by the attorneys, jurors began deliberating the penalty. San Bernardino County Superior Court Judge Richard Garner is not required to follow the jury's recommendation. The proceedings were moved to San Diego because of pretrial publicity.