A police detective has testified Scott Peterson rented a private mailbox the day before he reported his wife missing. Two weeks later, Peterson got a letter there from his mistress, Amber Frey (fry). Richard House's testimony emphasized the prosecution's contention that Peterson's love affair was his motive for the murder of his pregnant wife, Laci. But then prosecutors suffered another setback. House testified he found some of the Petersons' wedding pictures in a wastebasket in a storage unit. When he was asked on cross-examination whether he thought the pictures were being thrown away, House said no. It was the second time in a week a prosecution witness - a detective - shot down a prosecution theory. Last week, a detective testified tests on a plastic pitcher indicated it was not used to make cement anchors.