|Dates||???? - October 2018 (killed by Nick)|
|Location||Pike Creek, Delaware|
|Episode(s)|| 14.02 Gods and Monsters|
14.07 Unhuman Nature (flashback)
Arty Nielson was Nick's neighbor in Pike Creek, Delaware. Arty initially came forward after the death of Nick's family, telling the police he saw a man exit their home, but later recanted his statement.
When Nick becomes obsessed with finding out who killed his wife and son, he returns to Pike Creek where he pays a visit to Arty, questioning him about what he saw that night. Arty, however, tells Nick that there was no man that night and he only said he saw someone because he wanted to help Nick. Nick becomes increasingly more agitated and continues pressing a nervous Arty. Nick snaps and grabs Arty by the throat, claiming that someone got to him, while Arty continues proclaiming he remembered that night wrong and doesn't know anything. Nick does not believe him and proceeds to torture and kill Arty with a hammer.
A few weeks after Arty's murder, Nick tortures a priest that Arty had gone to confession to in order to find out what Arty had confessed about the murders. However, the priest refuses to break his vows and tell Nick who murders him as a result.
With the help of the reporter who covered the story of his family's murders, Nick tracks down ex-cop Frank Kellogg and reveals that Arty told him that he'd seen a cop running out of Nick's house on the night of the murders. After Arty told the police, they had threatened him into silence, apparently in an effort to protect one of their own through a cover-up. Nick eventually learns that the demon Abraxas was the true killer while he was using Frank as a meatsuit, explaining what Arty had witnessed.