Carlo passed away aged 61 following a five-year battle with amyotrophic lateral sclerosis (ALS), a degenerative neurological condition also known as Lou Gehrig's disease.
The author was famed for writing insights into the minds of mass murderers, including a 2006 best-seller about assassin Richard Kuklinski - also known as the Ice Man.
Rourke had been racing to complete his big screen portrayal of Kuklinski so Carlo could see the adaptation of his book, and the actor was devastated when he heard his friend lost his battle with illness.
He tells the New York Post, "I was friends with Phil for 30 years. I never met someone who suffered so much and who refused to quit."
Carlo was also fighting cancer at the time of his death. His funeral will be held in New York later this week (begs08Nov10).