methods of protecting someone who may be in danger as a result of agreeing to tell the courts or police what they know about a crime

an expert in witness protection 证人保护方面的专家

a system in which someone who has agreed to tell the courts or police what they know about a crime is protected, usually by preventing their address and identity from becoming known

The FBI told Cullotta that Spilotro had ordered a hit on him, and Cullotta entered witness protection. 联邦调查局告诉卡洛塔，斯普洛特罗下令暗杀他，卡洛塔因此进入了证人保护计划。

Brennan and his family were put into a witness protection programme with new identities. 布伦南和他的家人以新的身份加入了证人保护计划。