NYPD investigators say Pedro Hernandez gave very specific details about the murder and they feel confident he is the killer they have been looking for.
New York City Police say the 51-year-old Hernandez lured Patz into a corner store near the then-6 year old's bus stop by offering him a soda.
"He then led him in the basement of the bodega, choked him there and disposed of the body by putting it into a plastic bag and placing it in the trash," said Raymond Kelly, NYC Police commissioner.
Hernandez was a 19-year-old clerk at that store in 1979. Police finally zeroed in on him as a suspect after re-opening the cold case and digging up an apartment basement down the block from where Patz lived. They didn't find any evidence, but it prompted a relative to call with a key tip.
He spoke to one family member and to others in last 33 years about the fact that he's done something bad and "killed a child."
The married father was arrested at his New Jersey home. The motive for the murder remains a mystery.
The morning Patz vanished was the first morning his parents let him walk to the bus by himself. They never left the neighborhood after his disappearance. His father told ABC News just three years ago he and his wife always held out hope their little boy would come home.
"We didn't know what had happened to him, we didn't know where he might be, so of course the thought in the back of our minds was always that we should be here for him," said father Stan Patz.
Detectives say Hernandez, who is believed to have cancer, was remorseful and appeared to be relieved to finally tell his deadly secret.