Jen Nelson is the cousin of homeless street performer and serial killer Jonah Applebaum. She provided Applebaum a place to stay when he became homeless due to an accident that ruined his Olympic career and drug problems that exacerbated his paranoid schizophrenia, which left him estranged from his brother in California. She was the heir of his royalties he earned from a business based on his style, run by brothers Grant and Bob Carpenter. Applebaum stopped when her boyfriend Cal moved in because they hated each other.
Jen was questioned when Applebaum was suspected of three homeless men's murders on Randall's Island, which she was in disbelief from. However, she revealed Cal moved his things to the warehouse where the business ran its factory. It tied Applebaum to his killings, but not the three men's murders. The Carpenters were responsible, as they tried to kill Jonah but mistook his friend Paco and killed him instead, as Applebaum gave him his Olympic skates for Paco's birthday. Two other homeless men at the scene were killed, and one of the men's girlfriends narrowly escaped.
After the Carpenters were imprisoned, Applebaum was arranged for hospitalization and psychiatric treatment. (L&O: "Skate or Die")