A New Jersey man was in a “fit of madness” and experiencing “terrifying visions” when he allegedly murdered his younger brother, according to new details from the Mercer County Prosecutor’s Office.

A probable cause affidavit provides further details about the arrest of Matthew Hertgen, accused of brutally killing his brother and a cat, with police describing the crime scene, the body, and the reasons behind his other brother’s concerns regarding Matthew’s behavior prior to the event.

Matthew Hertgen may have been been suffering from severe mental illness for years before the alleged murder A plate and utensils smeared with blood were allegedly found inside the home of a Princeton,