[2] With the German agent Erich Gimpel, he was transported back to the United States by the U-1230, landing at Hancock Point in the Gulf of Maine on 29 November 1944.

Their mission, Operation Elster ("Magpie"), was to gather technical information on the Allied war effort and transmit it back to Germany using a radio they were expected to build.

Soon, Colepaugh abandoned the mission, taking US$48,000 ($830,800 today) of the currency they had brought and spending a month partying and carousing with local women.

[2] After spending $1,500 ($26,000 today) in less than a month, Colepaugh visited an old schoolfriend and asked for help to turn himself in to the FBI, hoping for immunity.

[2] The FBI was already searching for the two German agents following the sinking of a Canadian ship a few miles from the Maine coastline (indicating a U-boat had been nearby) and reports of suspicious sightings by local residents.

[8] Gimpel and Colepaugh are believed to have been the last Nazi German spies in World War II who reached the United States.