"I want him to be alive and call me before I leave this earth," Sherry Marino, 70, says of her son, Michael

After 40 Years of Doubt, DNA Tests Prove Victim of Serial Killer John Wayne Gacy Is Not Her Missing Son, Mother Says

For nearly four decades, Sherry Marino has faithfully visited her son’s grave every few weeks. Each time, she brings flowers and candles – and a heart filled with doubts.

Long ago, authorities told her that dental records confirmed that her son, Michael, was the fourteenth of 26 victims unearthed in the crawl space beneath the Chicago home of notorious serial killer John Wayne Gacy. But she never believed it was him.

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“I’d tell people, ‘Listen, I know that is not Michael,’ ” Sherry, now 70, tells PEOPLE exclusively. “I’d say, ‘Michael is out here somewhere.’ Not one person believed me – not even in my family. I said, ‘I don’t know where he is but he’s out there somewhere.’ ”

The clothing found with the body didn’t match what Michael was wearing the last time she saw him and it took investigators more than a year and a half to identify him, she says. Plus, she says she was with her son when he had a tooth pulled in March 1976, and the dental records of the deceased indicate no missing teeth.

Those were the purely logical reasons she knew it wasn’t Michael. There were some intangible ones as well.

“I would touch the grave and I felt nothing,” she says. “And I’d constantly talk to it: ‘Michael, if this is you, please give me a sign.’ There was always just nothing. Just completely cold.”

In 2012, Sherry had the body exhumed and got private DNA tests done on the remains. The tests showed the body was not related to her, she and her attorney, Steven Becker, say.

Next, because authorities also had said Kenneth Parker, Michael’s best friend who disappeared the same day, was a Gacy victim as well, she had his body exhumed in 2015, thinking it was possible the bodies had been mistakenly switched. Tests on that body showed no relation to Sherry either.

“In my heart I knew it wasn’t Michael,” she says. “I just always knew it wasn’t him. I can’t explain it.”

Still, her son’s case continues to haunt her.

“It’s something that never goes away,” she says. “It’s with me everyday.”

The Killer Clown

Gacy, who was known as “The Killer Clown” for his penchant for dressing up as Pogo the Clown, was convicted of murdering 33 boys between 1972 and 1978. He received a death sentence for twelve of those murders and was executed by lethal injection in 1994.

In 2011, the Cook County Sheriff’s Office launched an effort to identify eight victims. So far only one has been identified but the testing has led to the solving of twelve cold cases not involving Gacy.

A spokesman for the sheriff’s department declined to comment on the DNA testing, but Edward Pavlik, one of the forensic dentists who identified Michael from his dental records, is insistent that the body is his.

“I’m 100 percent certain,” he tells PEOPLE. “There are five fillings that are so distinctive. I’m a perfectionist. There is no question in my mind.”

He says he’s had 13 forensic experts compared the dental records. All came to the same conclusion he did.

He says it’s possible the bones of the victims got mixed up.

“These two bodies were buried together, one of top of the other,” he says. “Is it possible some of these body parts could have become comingled? Yes.”

But Becker, Sherry’s attorney, says he took the records to an outside dental expert himself.

“All I’m going to say is I found a direct inconsistency,” he says. “I had him look at Michael’s charts and compare it with the autopsy report. He had a much different conclusion than Dr. Pavlik does and the DNA now shows Dr. Pavlik is wrong.”

Adding to the confusion is that the jaws of the victims are no longer in good enough condition to examine, according to Becker, who says the sheriff’s office told him that. They were buried together in 2009.

“Over time water had gotten in and many of the ID marks on the jaws had been effaced and many of the jaws had been commingled, so they had been completely forensically compromised,” he says.

Of that statement Benjamin Breit, a spokesman for the Cook County Sheriff’s Office, would only say: “That’s unequivocally false.”

A Son Goes Missing

Michael was on his way to a local arcade the day he vanished. He left home around 2 p.m. on Sunday Oct. 24, 1976, Sherry says.

“I told him to be back by 6 because we were going to get the movies that night,” she says. “Michael was very punctual. If he said he’d be there at 6, he’d be there at 6. So I was very worried when it got to be 6:15 and he wasn’t home.”

She began calling the police around 9 or 10 p.m., she says. But they told her she had to wait until he was missing for 24 hours before they could do anything, Sherry says.

Michael was a “very kind, very good” kid who never got into trouble, she says. He was a drummer whose favorite song was Led Zeppelin’s “Stairway to Heaven.”

For the next two years, Sherry pounded the pavement looking for her son. When news broke about the Gacy victims found stacked together in the crawlspace underneath his home in December 1978, it didn’t cross her mind that her son was one of them, she says.

When I saw it, I thought, ‘Oh my God. Those poor parents. I feel so bad for them,’ ” she says. “I never thought he was ever a victim.”

Almost two years later, police told her dental records confirmed the 14th victim was her son.

As for what’s next, Becker says he hopes to get the DNA samples put into a national missing persons database to ascertain who they belong to.

Sherry hopes it finally leads to a reunion with her son.