“告密者”用英语怎么说？

哈得诺思上尉当然要求那个告密者离职了.Captain Hardnose certainly ran that rat over the hill.团夥中的一员后来变成了告密者.One of the gang members had turned informer.歹徒头目决定要将告密者用汽车绑架去干掉.The gang leader decided that the informer must be taken for a ride....