Arty lived in Pike Creek, Delaware where he was the neighbor of Nick and his family. On the night that Nick's family was brutally murdered, Arty, who had a window facing Nick's house, claimed to have seen a man run out of the house, but later changed his story. The man Arty saw running out was a cop and the police later threatened him into silence in an apparent cover-up to protect one of their own.
In 2018, following the death of Lucifer, Nick visited Arty in hopes of learning who his family's killer was and gaining revenge. Arty nervously claimed to have been mistaken about what he saw, frustrating Nick with his obvious lies. Believing that someone had gotten to Arty and made Arty change his story, Nick strangled Arty up against a wall and demanded answers. Nick eventually beat Arty to death with a hammer, the same way that his wife and son were murdered years before.
Nick later tortured the priest who Arty went to in confession to find out the name of the person Arty saw outside of his house. After the man refused to break his vows and tell Nick what Arty had revealed, even under torture, Nick murdered him too. Nick eventually tracked down former beat cop Frank Kellogg and revealed that Arty had told him that he saw a cop coming out of Nick's house the night of the murders but was threatened by the police to keep quiet in an apparent cover-up. Frank eventually revealed that he had killed Sarah and Teddy while possessed by the demon Abraxas.