The body of Sylvester Stallone's son may have lain undiscovered for up to a week, a US gossip site has reported.
Sage Moonblood Stallone was found dead in his Los Angeles home, leaving his action hero father grief-stricken as authorities investigate the cause of his death.
A source told TMZ that Sage's housekeeper had strict instructions not to enter his room, or even knock on the door.
Police sources told the website that Sage had been dead in the room for three or four days, and possibly as long as a week.
Sage reportedly lived like famous recluse Howard Hughes, spending days in a room littered with cigarette butts, beer and soft drinks cans, and rotting food.
"Sylvester Stallone is devastated and grief-stricken over the sudden loss of his son," said his publicist, Michelle Bega.
"His compassion and thoughts are with Sage's mother Sasha."
Sage was found on Friday afternoon by his housekeeper at his home on Mullholland Drive in the Studio City area of LA.
Police officers were called, and they confirmed he was dead.
Assistant chief coroner Ed Winter said no suicide note had been found.
Prescription bottles were recovered in the investigation, but Winter could not say what kind or how many, or whether they had a role in his death.
Winter said a post-mortem would be performed in the next few days and investigators would look into Sage's medical history.
But he said a cause of death was likely to take several weeks while toxicology tests were performed.
TMZ said its sources insisted Sage's death was almost certainly an accident.
George Braunstein, a lawyer who has represented Sage for 15 years, said friends and acquaintances had become concerned because they had not heard from him in the past day.
Sylvester Stallone appeared on Thursday at Comic-Con, the San Diego pop culture festival, to promote his upcoming film Expendables 2 with friend and co-star Arnold Schwarzenegger.
The 66-year-old left the convention and returned to Los Angeles after hearing of his son's death.
Sage Moonblood was the oldest of Stallone's children and the first of two sons he had with his first wife Sasha Czack.
Sage made his acting debut in 1990's Rocky V and also appeared with his father in the 1996 film Daylight.
The same year he teamed up with film editor Bob Murawski to co-found Grindhouse Releasing, a company dedicated to preserving and promoting the B-movies and exploitation films of the 1970s and 80s.
"He was very respectful of all the actors in all the movies," Braunstein said. "You couldn't mention a movie that he didn't know everything about."
Sage Stallone also directed the 2006 short film Vic, which screened at the Palm Springs Film Festival.
Braunstein said Sage had been planning on getting married, and received frequent requests to work on films.
"He was a full of life filmmaker with his whole future ahead of him," Braunstein said. "He was just very up and enthusiastic and positive."
Braunstein said Sage greatly admired his father, but had been working hard to make his own name in the film industry.
"He was very proud of his father and proud to be his father's son," he added.