Police on Wednesday unearthed a gruesome secret from a concrete tomb at the Newark, N.J., home where a notorious fake doctor once lived: the body of a woman believed to be a missing Manhattan investment analyst who was one of his patients.

New York Police Department investigators believe the body — stuffed into a suitcase under concrete — is that of Maria Cruz (search), 35, a Barclays Capital (search) analyst who was last seen at her Midtown Manhattan home April 13, 2003.

While cops did not have a positive identification pending an autopsy Thursday, sources said the remains matched Cruz's description, including her breast implants.

The woman may have been the victim of illegal surgery gone wrong.

"We are exploring the possibility that she may have died as the result of procedures he performed, but was not licensed to perform, including anesthesia," said an NYPD spokesman.

The property was once owned by Dean Faiello (search), who went on the lam last year after pleading guilty to charges of practicing medicine without a license.

Authorities decided to search the house at 212-214 Elwood Ave. in Newark during a probe into the whereabouts of Faiello, who is believed to have fled to Costa Rica.

He was exposed as a fake by a New York Post investigation during which the college dropout offered to remove a reporter's moles using laser surgery, which requires a medical license.

NYPD sources said they had evidence that Cruz went to Faiello for treatment on her tongue shortly before she disappeared.

He was interviewed by cops regarding the disappearance but said nothing then to raise suspicions.

The New York Attorney General's Office also investigated information that Faiello had several bags of concrete delivered to the residence around the time Cruz vanished.

Soon after that, someone noticed the slab in the renovated live-in garage.

Last Friday, NYPD detectives got permission from the home's new owner to inspect the slab.

On Wednesday, NYPD and Newark cops made the gruesome discovery.

Neighbors in the Forest Hill section were shocked that Faiello — who dressed as Dracula to give out Halloween treats — had a record.

"We knew he was a professional in New York, but we never knew what he did," said neighbor Isabel Kitzman.

Cruz, a Philippines native, was reported missing last April 16.

At the time, Faiello was free on $5,000 bail, following his bust the previous October for practicing medicine without a license at his Skin Ovations clinic in Manhattan.

On June 26, Faiello pleaded guilty to the charge, for which he faced up to four years in prison.

But the phony doctor — who also pleaded guilty to charges of writing fake prescriptions in 1999 — fled the country.

Cruz had an MBA from Fordham University (search) in the Bronx, where she got straight A's.

She moved up from a entry-level job at Citibank to a $180,000-a-year senior post at Barclays, where she had worked since July 2001 in high-yield bonds.

But Cruz had been depressed at the time of her disappearance, still carrying a torch for a boyfriend who had broken up with her.

Cruz had a self-image problem, prompting her to have her breasts enlarged and to have fat removed from her face.

"I'm still hoping she's somewhere and still alive — and no one can take that from me," said Cruz's uncle, José Navarro.

Cruz's family in the Philippines is hanging on to a sliver of hope.

"We tried to give them hope, because nobody's sure if it's her," Navarro said.