Prosecutors and defense attorneys will pick six alternate jurors today for the trial of the man accused of killing a seven-year-old San Diego girl. Six men and six women were sworn in yesterday for the trial of David Westerfield. Westerfield has pleaded innocent to charges of murder, kidnapping and misdemeanor possession of child pornography. If convicted, he could face the death penalty. Danielle van Dam vanished from her bedroom in early February. Her body was found three weeks later alongside a rural road east of San Diego. Opening statements are scheduled to begin Tuesday.