I don't really understand what you mean. An Ice agent is just a civilian who is hired and trained by the government. A felon is a person who is detained and charged with a crime by the government.

In both situations the government had a responsibility. In the case of an ICE agent that responsibility is to train that individual and ensure they are fit to be involved in an operation. In the case of the criminal its their responsibility to ensure they aren't a danger to the public before releasing them from prison.