(Salem, OR) -- A wrongful death lawsuit is being filed against the City of Salem and police officer Nathan Bush over the fatal shooting of a man with a history of mental illness. In July of last year, Arcadio Castillo the third allegedly assaulted his mother in their home, and she called police for help. The lawsuit alleges that Bush entered the home without backup and shot Castillo before giving him a chance to drop the knife he was holding. Prosecutors say Castillo ran toward Bush and he opened fire, killing him. A grand jury determined Bush was justified in the shooting.