Barney Snodgrass was the social services coordinator before Mark Lilly and used to be Callie's boyfriend. He was sent to a mental hospital for killing Erik. He escapes 5 years later to seek revenge on everyone in the Department of Integration, in the episode "Fools for Love".
Barney loves pranks. He believed in teaching through public humiliation and cruelty in the DOI. However, when he was at the receiving end of a prank on April Fools' Day five years ago, he lashed out and stabbed Erik to death. That was how Erik, originally a human, got rebuilt into a robot. Francis Grimes arrested Barney and sent him to the New York City Mental Hospital.
Barney escapes the mental hospital on Grimes' car after Grime has made a joke on a clown there on April Fools Day. Mark finds the guys from the DOI in a safe room and is told about Barney's story and escape. Barney's prison journal has been found recorded on a roll of toilet paper. When the bunnycorn janitor is found murdered, everyone rushes to Grimes' mountain cabin. Callie tells Mark that Barney is her ex-boyfriend in the van.
At the cabin, Barney murders Twayne, Croatian Man, Erik, Doug and Toby. He captures Mark and Grimes and puts on a game show where he and Mark compete for Callie's love. Barney wins back Callie with his evil nature. Mark is enraged and breaks free of his bond. He wrestles away Barney's knife and raises it high above his own head to stab Barney.