NEW YORK (CBSNewYork) -- The excavating equipment was silenced Friday night, but earlier in the day, investigators were hard at work searching for 6-year-old Etan Patz.
As the NYPD and FBI continued looking for answers, sources told 1010 WINS that investigators were interviewing other people in connection with the case.
Work crews hauled in a dumpster earlier as investigators broke up the concrete basement floor of 127 Prince Street with jackhammers and busted through brick walls looking for clues in the decades-old disappearance. The concrete chunks will be deposited into a container for later examination, CBS 2's John Slattery reported.
"We're cautiously optimistic we'll find evidence," FBI spokesperson Tim Flannelly said.
1010 WINS' Juliet Papa reports
Smaller pieces of concrete were removed by hand and surface dirt was sifted by hand. Once that is complete, investigators will start to dig.
"Today they're beginning a more systematic digging into the earth," Deputy Commissioner Paul Browne said.
WCBS 880's Rich Lamb reports
Police Commissioner Ray Kelly told reporters that crews are expected to continue their search for another 4 to 5 days.
Othneil Miller, a handyman who once worked in the building and used to pay Patz for small chores, is a person of interest in the case, police said. At the time Patz disappeared, Miller allegedly put down a new concrete floor in the basement.
Miller also asked investigators "What if the body was moved?" when he was questioned by authorities recently, sources told CBS 2.
1010 WINS' Stan Brooks Hears From Commissioner Kelly
A cadaver dog picked up the scent of human remains Thursday deep in the walls of the building that is just a block and a half away from where Patz lived.
Stephen Kuzma, the building manager at the time of the disappearance, said Miller had a workshop in the basement.
"Every time I went down there, it seemed there was a different wall," Kuzma told CBS 2's Kathryn Brown. "It's a maze."
Dr. Lawrence Kobilinsky, Chairman of the Forensic Science Department at John Jay College, said the search is not a wild goose chase.
"We have a person of interest, we have a location and now the dog is alerting. So there's reason to believe that there's something significant about this particular site in the basement," Kobilinsky told 1010 WINS' Terry Sheridan.
1010 WINS' Terry Sheridan Speaks With A Forensic Expert
Even after 33 years, modern-day technology can determine if Patz is buried or perhaps was killed in the building, according to Kobilinsky.
"The bottom line is after 33 years under these conditions, a body buried in soil and then covered with concrete, there are still molecules that remain and can be detected," he said.
Kobilinsky also told CBS 2's Tony Aiello "If Etan Patz is buried at this site, there will be skeletal remains. Obviously, soft tissue will be completely decomposed. There may be hair, but...skeletal remains and perhaps clothing."
The little boy was last seen walking to catch a school bus on May 25, 1979. Patz's parents let him walk to the bus alone for the first time that morning and he was never seen again.
"This location figured in the original investigation," Browne said. "The decision was made to come back, apply probably the best forensic expertise in the country between the FBI and NYPD."
1010 WINS' John Montone reports
For 33 years, the little boy has remained in the hearts and minds of residents in the neighborhood and as the search continues, many are hopeful.
WCBS 880's Marla Diamond reports
"You stop and think what the parents must go through and what's happened to them over the years," said neighbor Bob Loeser. "I hope something comes about it, if it's true, and he's there, at least they'll know."
"I'm very hopeful that this will bring closure to the family," said resident Sean Sweeney.
Patz's disappearance captivated the entire country. His was one of the first faces to be shown on a milk carton and his case created a cultural shift, changing the way parents raised their children.
"You just don't see kids walking to school alone unless they're quite old now," said parenting expert Carol Evans. "People just don't put kids on the bus without being right directly there at the bus, even in the suburbs."
Investigators are cautiously optimistic they'll find evidence that could finally bring some closure to Patz's parents, who never moved away or changed their phone number in hopes that their little boy would someday return home.
Patz's parents are not commenting right now and have a sign posted on their front door asking for privacy.
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