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Defense calls biomechanics expert to stand in murder trial

Cause of injuries comes under studied scrutiny
By: Jenifer Gee, Journal Staff Writer
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A defense witness in an Auburn man’s murder trial testified Tuesday that evidence suggests William “Billy” Moon was not the driver during a car accident that took the life of his close friend more than two years ago. Rick Robertson, who has a Ph.D. in biomechanical engineering, took Tuesday morning to present his analysis of the fatal car crash that happened on Bell Road in Auburn in June 2006. The crash involved Auburn’s Moon, 23, who is charged with second-degree murder and gross vehicular manslaughter while intoxicated for the June 3, 2006 death of 20-year-old Stewart Shapton, who was in the car at the time of the crash. Moon has pleaded not guilty. The prosecution contends that Moon was driving the 2004 Infiniti G35 at the time of the accident. The defense argues that Shapton was the driver. Robertson testified that Shapton’s injuries were consistent with the impact on the driver’s side of the vehicle from the crash. During his PowerPoint presentation, Robertson showed computer-generated images of how the vehicle hit a line of trees alongside the road. The images also showed how the crash would’ve impacted the driver and passenger. Robertson said repeatedly that he thought Shapton’s injuries were consistent with injuries that would’ve happened as a result of the driver’s side of the car crushing inward. He also stated that he was not sure there was any other explanation for the injuries being as the passenger’s side had substantially less visible damage. An autopsy report indicated that Shapton suffered multiple traumatic injuries including a laceration to the back right side of his skull, fractured ribs, a lacerated liver and multiple cuts and abrasions. Sacramento defense attorney Clyde Blackmon had Robertson compare Shapton’s injuries with those of Moon. Moon was life-flighted from the scene and later treated for a broken neck, a cut to the nose, a concussion and cut in the back of the head. One of the key areas the defense and prosecution focused on were injuries to both men’s feet and lower portions of their legs. Robertson said Shapton’s cuts and scraps on his lower legs and feet were consistent with injuries that would occur from hitting or scrapping the driver’s side gas and brake pedal. During cross-examination, Prosecutor Stephanie Macumber asked if Robertson had ever been shown any pictures of Moon’s feet and legs. Robertson said he had not but said the number of Shapton’s injuries made it more likely he was the driver. She pointed out a hospital report that documented a laceration to the inside of one of Moon’s feet. The defense and prosecution also argued over the cause of a significant injury to Shapton’s left hand. Robertson said it was possible the metal pillar closest to the driver’s seat had crushed in far enough to damage his hand. Macumber asked if Shapton’s hand had been broken, given the supposed great force with which that pillar was moved in. Robertson responded that the hand was not broken. The Moon trial is expected to continue at 9 a.m. Thursday in Dept. 42 located at the Bill Santucci Justice Center in Roseville. The Journal’s Jenifer Gee can be reached at or post a comment at auburnjournal.com.