An Arkansas lawyer and his son will soon be heading to prison after pleading guilty to mailing a threatening communication ? a poisonous snake.

Bob Sam Castleman, an attorney and former city judge in Pocahontas, Arkansas, and his son, Jerrod, were charged with mailing a cardboard box containing a venomous copperhead snake to a neighbour with whom they had feuded. The two pleaded guilty in federal court.

The wife of the man to whom the poisonous package was addressed opened the box and saw the snake, about 28 inches long. Police soon arrived on the scene in Pocahontas, about 140 miles northeast of Little Rock, and shot the snake dead.

The elder Castleman faces between 27 months and 33 months in prison, while his son faces a longer term of between 31 months to 44 months on the same charge because he had a previous conviction. A sentencing date has not been set. Both men tried to enter a guilty plea but the proceedings were delayed when both tested positive for illegal drugs. Among the evidence presented to the court were fingerprints on the box that matched those of the accused and the carcass of the snake. Its fangs were intact, but its body had been sliced in half.