By Natasja Sheriff

NEW YORK (Reuters) - The attorney for a former deli worker accused of murdering a New York boy in 1979 argued on Monday that his confession was unreliable and improbable and that prosecutors failed to present evidence of his guilt.

Pedro Hernandez, 54, charged with kidnapping and murder, confessed to police in 2012 that he choked 6-year-old Etan Patz, stuffed him in a box and left him in a New York alley.

Patz vanished as he walked alone for the first time to a school bus stop in his Manhattan neighborhood on May 25, 1979. His disappearance sparked a national movement to find missing children and his picture was one of the first to appear on milk cartons.

Patz has never been found but was declared dead in 2001. There was no forensic evidence presented at Hernandez' trial in state Supreme Court in Manhattan.

Defense attorneys say the Hernandez confession was coerced by police. They say Hernandez, arrested in 2012 on a tip that he had confessed to a church prayer group in New Jersey, is mentally ill, intellectually disabled and suffers hallucinations.

"Pedro Hernandez is the only witness against himself. The stories he told over the years, including in 2012 and since, are the only evidence," defense attorney Harvey Fishbein said in his summation to the jury.

Hernandez' confession, made after more than six hours of police interrogation, was inconsistent and unreliable, he said.

"His story is filled with improbabilities and impossibilities," Fishbein said.

In his confession videotaped by police, Hernandez described luring Patz into the deli where he worked with the offer of a soda, taking him to the basement and strangling him.

Defense witnesses testified that Hernandez suffered a "schizotypal personality disorder," could not distinguish between what is real and what is imaginary and was at risk of confessing falsely because of intellectual disabilities.

Defense attorneys lay the blame on Jose Ramos, who dated a Patz family babysitter and was long considered the prime suspect. Convicted of sexually abusing boys, Ramos is in prison.

If convicted, Hernandez faces the possibility of life in prison.

Jury deliberations were set to begin after prosecutors present their closing argument on Tuesday.

Listening to the court proceedings were the missing boy's father and sister, Stan and Shira Patz, as well as the defendant's wife, Rosemary, and daughter Becky Hernandez.

(Editing by Ellen Wulfhorst, Bill Trott and Peter Cooney)