CHICAGO (CBS) — An orthodontist who helped identify victims of serial killer John Wayne Gacy is defending his work, after a Chicago woman got a judge’s consent to exhume the body she doesn’t believe was her son.

As WBBM Newsradio’s Mike Krauser reports, Dr. Edward Pavlik says he has absolutely no doubt – the dental comparison he did three decades ago was solid, and the body – Gacy victim No. 14 at the time – was, and is, that of Michael Marino.

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LISTEN: WBBM Newsradio’s Mike Krauser reports

“The dental identification is a rock-solid thing,” Pavlik said. “Once we get X-rays, there’s just no question as to what the identification is. I’m a fanatic perfectionist. I would not sign off on something, obviously, that would not be 100 percent correct.”

Pavlik says he got the records from the evidence locker where they’ve been stored, and went over his work again last week and confirmed his findings.

Michael Marino’s mother has always doubted the grave she has visited for 30 years is that of her son.

Michael went missing on Oct. 24, 1976, at the age of 14, but wasn’t identified as one of Gacy’s 33 victims until 3 1/2 years later.

His mother, Sherry Marino, recently got the old records, and a comparison showed the body had a molar that her son’s chart from 7 months earlier did not show.

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Pavlik says the molar could have appeared in those seven months, and adds it would not be a criterion for identification.

Meanwhile, Cook County sheriff’s police are gathering leads on eight unidentified Gacy victims who were being exhumed in the summer. Lab experts took DNA samples and compared them against the DNA of possible parents, siblings and children, and as of Thursday had 25 legitimate leads.

Gacy, an ex-convict with a history of sodomy, worked as a contractor on Chicago’s northwest side and northwest suburbs in the years immediately preceding his arrest. He was a Democratic precinct captain and worked as a clown at children’s parties.

John Wayne Gacy

John Wayne Gacy was known for many years around his neighborhood as a Democratic precinct captain and a birthday party clown. But in December 1978, police discovered 29 bodies buried in a crawl space of his house and the surrounding yard in unincorporated Norwood Park Township. Another four bodies were found in the Des Plaines River. (Credit: CBS)

He was arrested on Dec. 20, 1978, after police discovered 29 bodies buried in a crawl space of his house and the surrounding yard of his house at 8213 W. Summerdale Ave. in unincorporated Norwood Park Township. They were covered with lime and encased with plastic.

Another four bodies were found in the Des Plaines River.

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Gacy was convicted of the murders and sentenced to death. When he was executed on May 10, 1994, his notorious last words were, “Kiss my ass.”