Updated

NEW YORK -- Six-year-old Etan Patz vanished on May 25, 1979. One of the most extensive missing-child searches was mounted to find him, but two decades later, the boy was officially declared dead. No one has ever been arrested.

Now, the Manhattan district attorney's office will take a fresh look at the evidence collected against the prime suspect, a convicted child molester serving 20 years in prison in Pennsylvania.

By looking into the cold case, Cyrus R. Vance Jr. will be making good on a campaign promise. A spokeswoman for Vance said Wednesday she could not comment further on an open investigation.

Etan Patz vanished while walking from his lower Manhattan home to a bus stop two blocks away. His disappearance spawned the national movement to publicize the cases of missing children. His photo was the first put on a milk carton, and his case turned May 25 into National Missing Children's Day.

The longtime former district attorney, Robert Morgenthau, said repeatedly he didn't have enough evidence to charge anyone. But Etan's father, Stan Patz, said that while there is little forensic evidence, he believes there is enough to convene a grand jury and get an indictment.

"All we have been asking for is the district attorney to take a good look at the information," Patz said. "I realize this is not like `CSI.' That's why it's been a tough case all along. But there is enough evidence that a competent attorney can use to prosecute."

Jose Ramos, who had dated Etan's baby sitter, has been the prime suspect all along, according to the boy's family. Ramos allegedly admitted to Pennsylvania authorities that he tried to molest Etan on the day of the child's disappearance but has denied harming him. It was unclear Wednesday if Ramos has an attorney, and Ramos was unreachable at the prison.

After Etan's disappearance, his parents kept the same number and stayed in the same SoHo apartment, in case he returned. But in 2001, after waiting 22 years, they obtained a court order declaring the boy dead.

In 2004, a Manhattan judge ruled Ramos was responsible for the boy's disappearance and presumed death, after the inmate ignored orders to answer deposition questions for a lawyer for the boy's parents. He was later ordered to pay $2 million to Etan's family.

Ramos is to be released in 2012 after a 20-year sentence for sexually abusing an 8-year-old boy, bringing a certain urgency to the case, which was never officially closed, the boy's father said. At least one FBI agent and a New York Police Department liaison is assigned to the case.

Patz is hopeful a fresh pair of eyes will yield some results.

"He (Vance) says he's willing to do that, and the fact he's willing to say it in public is very encouraging," Patz said.