We recently had a situation where a cop blew a red light and caused a series accident. He blamed the driver of the other car, who was illegal and did not speak English, and gave her several tickets thinking there were no independent witnesses to dispute his version of events, which occurred in the early morning hours. Little did he know that my friend, who is a late night techie, had stepped outside his office for a smoke and witnessed the whole thing.
Myself, I would have reported the illegal to the INS. It's too bad that your buddy didn't seem to think that a non English illegal immigrant driving around is a threat to public safety. That illegal shouldn't have been on the road in the first place.