Local and federal authorities were investigating reports Monday that someone left a severed pig's head at a North Philadelphia mosque. An employee at the Al Aqsa Islamic Society mosque found the bloodied head when he arrived around 6 a.m. Monday. Surveillance video at the site, along Germantown Avenue, captured a red pickup truck that drove twice past the mosque just before 11 p.m. Sunday. On its second pass, someone threw an item from the passenger window, the video shows. Pigs are considered insulting to Muslims who observe halal dietary laws.