A man was found decapitated in the bathroom of his Staten Island home in New York, and his teenage stepson has been taken into custody in connection with the killing, police sources told NBC New York.The victim’s sister arrived at their Cary Avenue home in West Brighton after 4pm on Monday and saw trails of blood throughout the house, police sources said. She then discovered the decapitated victim in the bathtub.A knife was still in the 45-year-old man’s neck when police arrived, sources added.The victim, whose head was reportedly severed from his body, was declared dead at the scene, police said.The 19-year-old stepson of the victim’s girlfriend was arrested at the location but has not yet been formally charged, sources and friends told New York Post.His mother said he has a history of mental illness.A neighbour reacted to the killing, saying, “This whole world is upside down. This is like a terrible, horrible, to do this to a person you know not even to an animal, you don’t do that.”Hugh Nembhard, who has lived across the street for about 60 years, told Eyewitness News, “I’m not familiar with the stepson. I never saw him. I saw the father, but never the stepson. I don’t know what to make of it. I don’t know what to make of this. This is a shock to me. The neighborhood has changed.”