Opinion ID: 1990867
Heading Depth: 3
Heading Rank: 1

Heading: Error by Firearms Expert

Text: [¶ 30] At trial, the State's theory was that a Taurus Model PT-99-AF was the murder weapon. This gun was never located, but there was evidence that Cookson had possessed it. Shell casings known to have been fired from this gun were obtained by the police and examined by Bachelder, a firearms expert. It was his opinion that the Taurus Model PT-99-AF was the murder weapon because characteristics of shell casings found at the murder scene were the same as characteristics of the casings obtained from former owners of this gun. After trial, Bachelder learned, when he read an article about the class characteristics of the gun, that he had mistaken a class characteristic for a unique characteristic. He promptly notified his supervisor that his testimony had been in error. The court made a factual finding that neither Bachelder nor the State knew at the time of trial that his testimony was erroneous. [¶ 31] Although Bachelder's error was not discovered until after trial, there is a question as to whether it could have been discovered by reasonable diligence before trial. Cookson, who must prove by clear and convincing evidence that he could not have discovered the error before the trial, failed to meet this burden. There is no evidence that he attempted before trial to obtain an expert to independently compare the shell casings found at the murder scene with those obtained by the police from former owners of the gun. Nor is there any evidence that he sought to obtain an expert's advice on shell casing characteristics. He did not cross-examine or in any way challenge Bachelder's trial testimony. [¶ 32] Additionally, Cookson has failed to prove that the outcome of the trial would have been different had Bachelder's error been discovered before trial. At trial another firearms expert, Charles Helms, testified that bullets obtained by the police from the yard of Cookson's house in New Gloucester had been fired from the same gun that fired the bullets obtained from the murder scene and the Gould autopsy. This evidence was independent of Bachelder's opinion and was based on the spent bullets and not the shell casing characteristics. Because Cookson has not shown that he could not have discovered the error in Bachelder's opinion prior to trial and has not shown that the outcome would have been different had he discovered the error, he is not entitled to a new trial on the basis of Bachelder's error.