According to an FBI affidavit, Maher's son overheard what the officer had said and asked his father about it.
The father "was irate," the affidavit said. "Maher told his son that they would have to leave again and threatened to kill the person who tipped the police off about his identity."
The Feds found four illegal firearms in the home where he was apprehended. Several other people were at the home, and were soon identified as family members, Nixon said.
He was charged with being an illegal alien in possession of firearms and was turned over to Immigration and Customs Enforcement, where he is being held without bond.
Maher appeared before a federal judge Thursday afternoon for his initial appearance in the gun case. His next court appearance is Feb. 22 and he will be held by the U.S. Marshal's Service until then.
It is unclear if he has been charged in the U.K. for the nearly 20 year old robbery.