Ex-chemical depot worker faces prison after fairness of trial upheld By Pamela Manson The Salt Lake Tribune     A former Deseret Chemical Depot supervisor convicted of falsifying air quality results lost his bid for acquittal when a federal judge ruled that witnesses at his trial had obeyed the rule barring them from discussing their testimony with one another.     At a Friday hearing, U.S. District Court Judge Tena Campbell also ruled that a witness at the trial of David James Yarbrough did make an incorrect statement about whether a manual on air quality tests was the latest version being used, but said the testimony was an honest error and did not affect the jury's decision.     The judge set sentencing for Jan. 13 for Yarbrough on seven counts of making false statements to a government agency. He faces a maximum sentence of five years in prison on each count.     Defense attorneys had claimed that a key witness might have spoken to other witnesses before they took the stand at the July trial, which might have influenced their testimony. They had asked for a new trial or an acquittal.     At Friday's hearing, three workers at the depot said they saw a supervisor who already had testified speak to another supervisor before his turn to testify, but were unable to hear the conversation.     The two supervisors testified that they did talk but were not discussing testimony.     Yarbrough was accused of omitting data or misreporting test numbers so monitoring units, which determine whether any toxic gases at the weapons destruction facility are being released, falsely appeared to be working. He adamantly denies the allegations and said after his conviction that safety had always been his paramount concern.     Under an international treaty, workers are destroying the nation's stockpile of chemical weapons at the depot, which is about 40 miles southwest of Salt Lake City. Yarbrough, a worker at the Oquirrh Mountain Facility Plant at the depot, had been a civilian employee there for more than 20 years.     pmanson@sltrib.com