Oh my God

From AP:

On April 25, Gregory Despres arrived at the U.S.-Canadian border crossing at Calais, Maine, carrying a homemade sword, a hatchet, a knife, brass knuckles and a chain saw stained with what appeared to be blood. U.S. customs agents confiscated the weapons and fingerprinted Despres. Then they let him into the United States.

The following day, a gruesome scene was discovered in Despres' hometown of Minto, New Brunswick: The decapitated body of a 74-year-old country musician named Frederick Fulton was found on Fulton's kitchen floor. His head was in a pillowcase under a kitchen table. His common-law wife was discovered stabbed to death in a bedroom....

At a time when the United States is tightening its borders, how could a man toting what appeared to be a bloody chain saw be allowed into the country?