Busse was riding her bike on the sidewalk on Lampson Avenue in Seal Beach with her 15-year-old son when Trujillo plowed into her. She was thrown from her bike and landed nearby.
Witnesses detained Trujillo until police arrived. He was found to be driving under the influence of prescription drugs including Oxycontin, Vicodin, Xanax and Soma. His blood alcohol level was .11 percent.
Catherine Busse died at the scene, but her son Samuel Busse was taken to the hospital with minor injuries.
Trujillo had a 2002 conviction for DUI. During the trial, prosecutors presented evidence that he used four different pharmacies to get up to 180 Vicodin pills and 120 Oxycontin pills every month.
Trujillo is due to be sentenced Aug. 20, 2010.