NEW YORK – For decades, the prominent case of a missing 6-year-old had a prime suspect: an admitted child molester in a Pennsylvania prison. Although the inmate has never been criminally charged in Etan Patz’s 1979 disappearance, he was found responsible in a wrongful-death lawsuit.

But investigators Friday continued tearing up a Manhattan basement linked to someone else, a handyman who was recently re-interviewed by authorities. Through a lawyer, he denied having anything to do with Etan’s vanishing, which helped turn missing children into a nationwide cause.

Authorities said they had yet to find any new evidence as of Friday, and the police commissioner and the FBI said they wouldn’t discuss any possible suspects. It’s unclear what the renewed investigation may turn up, if anything.

But if it leads definitively away from Pennsylvania prisoner Jose A. Ramos and to someone else, it could create a legal conundrum: one person held accountable for the boy’s death in civil court while another became the focus of a criminal case.

On Friday, investigators were using jackhammers and saws to carefully break through the basement’s concrete floor, pulling rubble out and carrying it out of the building with gloved hands, as an anthropologist stood by in case any human remains were found. The work concluded for the day around 6 p.m. but was expected to continue over several days.

The debris was to be taken elsewhere and tested, a process that could last into next week, chief police spokesman Paul Browne said.

Police were using a chemical that can spotlight traces of blood and expected that X-ray equipment could help them peer behind walls, though some walls were being removed, Commissioner Raymond Kelly said.

“We’re hopeful that we can bring some level of comfort to the parents, perhaps find some — obviously, the body of this poor child — but evidence that may lead to a successful investigation in this case,” Kelly said.

He was a lieutenant working on organized crime cases when Etan vanished on the first day he was allowed to walk to his school bus stop alone.

As for whether authorities were optimistic, Kelly said, “I really can’t say.”

The basement is in a building that was on Etan’s way to the bus stop from the SoHo building where his parents still live. At the time, handyman Othniel Miller, who was friendly with the Patz family, was using the underground space as a workshop.

Miller, now 75, is cooperating with investigators and had “no involvement in this tragic event,” his lawyer, Michael C. Farkas, told journalists gathered outside Miller’s Brooklyn home Friday.

Investigators decided to refocus their attention on the building after recently speaking again to Miller, whom they had interviewed several times over the years, according to a law enforcement official who spoke to The Associated Press on condition of anonymity because the investigation is ongoing.

Etan’s parents, Stanley and Julie Patz, posted a notice on their buzzer Friday telling reporters that they wouldn’t comment on the developments. A lawyer who has represented them is out of the country and didn’t immediately respond to phone and email messages.

Among the first vanished children to appear on a milk carton, Etan became a symbol of a movement to draw attention to child safety. The day of his disappearance, May 25, became National Missing Children’s Day.

The case has bedeviled investigators as leads emerged and fizzled over the years; Etan, never found, was officially declared dead in 2001.

Ramos, a drifter whose girlfriend was Etan’s sometime baby sitter, has been publicly floated as a possible culprit since the 1980s. Now 68, he is serving a 10- to 20-year sentence in Dallas, Pa., after pleading guilty to abusing an 8-year-old boy at a campground there. He is due to be released in November. Efforts to reach lawyers who have represented him were unsuccessful Friday.

A former federal prosecutor who had worked on the case, Stuart GraBois, declared in 1998 that he believed Ramos was behind Etan’s disappearance and death; efforts to reach GraBois on Friday were unsuccessful. A Manhattan civil court judge held Ramos responsible in 2004, saying that his refusal to answer some questions amounted to not responding to the suit. The judge ordered him to pay $2 million to Etan’s father, Stanley.

Police investigated leads to Ramos at various points, including a 2000 search of the basement of the building where he lived in 1979. But the Manhattan district attorney’s office concluded there wasn’t enough evidence to charge him, or anyone else. Former District Attorney Robert Morgenthau, who led the office from 1975 to 2009, declined to comment Friday.