Why wasn't Frank a suspect right away?

I love this movie but whenever I watch it, when they get to the part where the FBI agents are surprised to find out that not only did he change his name but he also has a criminal record, I wonder why the heck they hadn't already figured that out and added him as a suspect.

Once upon a time there was a magical place where it never rained. The end.

They didn't think that the terrorist was one of the pagent staff members so it's doubtful they ran background checks on all of them