Harold Delmar Sr. was stabbed inside the house, on Mason Avenue, just before 4 a.m. Wednesday.
He was stabbed twice, to the neck and chest, and pronounced dead at nearby Staten Island University Hospital North.
Detectives immediately launched a search for Delmar's son, who lives in a tent in the backyard of his father's house. They reportedly wanted to question him in connection with the murder. Soon after, the son's body was discovered in New Jersey.
Sources say Delmar, a father of 7, took care of his 79-year-old wife, who suffered from dementia. Two of his children reportedly lived in the back apartment, while the son, described as homeless, lived in the tent.
The son's body was found in a burned out car in Bayville.
The police investigation is ongoing, but it appears, officials say, to be a murder suicide.