The net result of the long police investigation is that the identity of the killer is still a complete mystery.
警方经长时间调查, 结果凶手的身分仍全然不知.
The journalist did not want to reveal the identity of his informant.
那个新闻工作者不想透露消息提供人的身分。
A credit card is not a valid proof of identity.
银行发的支票保付卡不是有效的身份证明文件。