immigrant visa in the passport that is not valid (missing pages)

My nephew has an immigrant visa in the passport. when he was going through customs to go to USA, agent found that there were pages missing from his passport. Passport is confiscated. what is the process to get visa for a new passport? is there anything that he needs to worry about.
thank you
The process of getting a new visa would be the same as the one through which he got the previous visa. Also, removing the pages from the passport might raise some questions at the interview.