One woman’s nagging intuition that her son was killed by serial killer John Wayne Gacy has proved correct. Sherry Marino last saw her son Michael alive in 1976 but her attorneys announced Thursday that the man buried in her son’s grave was not Michael.

Last year the grave was exhumed at the DNA found in the corpse did not match that of Michael Marino, according to the Associated Press.

“We don’t know who it is, but this is not her son,” said his mother's attorney, Steven Becker.

The confirmation came because of dental records. A jawbone and section of a femur were also tested for DNA.

“The dental identification is just 100-percent solid, absolutely no question,” said Edward Pavlik, who ran the tests. “We compared 32 teeth, probably half a dozen of them had very distinct fillings and every tooth was consistent with the dental records of Michael Marino.”

Gacy was executed in 1994 after he sexually assaulted and murdered at least 33 teenage boys and young men, burying 26 of them in the crawl space in his Chicago- area home. The murders took place from 1972 to 1978, during which time Gacy was employed as a children’s party clown.

Gacy is also known to have thrown multiple corpses off a bridge into Des Plaines River, at least one of which he thought landed on a passing barge.

Questions came up around Michael Marino as soon as 1978 because investigators counted him among the unidentifiable bodies stored in Gacy’s attic. Even at the time, though, Marino’s mother provided police with dental information and told law enforcement the clothes he was wearing did not match anything in his wardrobe.

The attorneys told the Associated Press that the new finding doesn’t necessarily exclude Marino from being one of Gacy’s victims as he could have been misidentified as another victim. Michael was just 14 years old when he disappeared.

The Chicago Tribune reported in October of 2011 that Marino said her son never broke his collarbone, another difference from the corpse buried beneath the Michael Marino’s headstone.

“There are discrepancies between the autopsy report and Michael Marino’s medical records,” the presiding judge said last year. “Certainly there’s been great advancement in medical science…”

The Marino family paid for the exhumation and DNA testing on their own with help from a community fund.