A man accused of crossing into Canada while posing as an agent for a fictitious agency was arrested when he returned to the United States, federal officials said Tuesday.

Leonard Hugh Fuller asked agents at the Eastport, Idaho, border crossing on July 9 if he could store his gun there while he went on vacation in Canada, according to court records.

He showed the officers a badge and credentials and they agreed to hold his 9mm Beretta until he returned, the records showed.

Border agents then checked with the U.S. State Department, which had never heard of the "United States Special Response Department Anti-Terrorism Unit" -- the agency Fuller reportedly said was his employer. Fuller was arrested when he returned July 12 and asked for his weapon back.

Fuller, 55, was booked for investigation of producing fraudulent identity documents, a federal felony punishable by a maximum 15 years and $250,000 in fines.

Immigration and Customs Enforcement agents interviewed Fuller and said he told them he made the credentials and bought the badge after starting a private security firm, the "United States Special Response Department."

Fuller said he had registered his company with the government but had lost all of his paperwork in a flood, according to court documents.

Nancy Cook, assistant U.S. attorney for the District of Idaho, said investigators were trying to determine where Fuller lives.

A public defender working on his case did not return a call for comment Tuesday.