In 1990, Kleasen moved to Barton-upon-Humber, Lincolnshire, England. He married local woman Marie Longley, who he met as a pen pal while living in the US. He ingratiated himself with local residents, and began to amass a huge gun collection. A firearms license officer became suspicious of Kleasen's claims of being a decorated military veteran and CIA agent, and confirmed from U.S. military officials that Kleasen had never served in the U.S. armed forces. This information was passed on to police, resulting in a more thorough background check on Kleasen.