Anthony Pasquale says Justin Robinson's parents should have known their son was troubled and gotten him help.
The 16-year-old boy is serving 17 years in prison for the murder of Autumn Pasquale in Clayton, Gloucester County.
The lawsuit claims Robinson's parents all but abandoned their son in the years before the murder, and when they were around subjected him to domestic abuse.
Robinson has admitted strangling Pasquale, who went missing while out riding her bike.
Her disappearance in October 2012 touched off a massive search that ended when her body was found in a recycling bin just blocks from her home.