phrase to give evidence against someone else in this way: 供出同案犯的罪证;揭发其他案犯 He was allowed to go free as a reward for turning Queen's evidence against his former accomplices. Moore agreed to turn Queen's evidence in exchange for not being prosecuted. One of her former associates had already turned Queen's evidence. It was hoped he might be persuaded to turn Queen's evidence. In the end, he escaped prosection by turning Queen's evidence. See also