A spray-painted smiley face is reportedly appearing near the sites where college-aged men are found dead, often in a body of water. Although nearly all of the cases have been classified as accidental or undetermined drownings, there's a theory that at least 40 of these victims have been killed by an organized underground gang referred to as the “Smiley Face Killers.”

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Retired NYPD detective Kevin Gannon and his team of "Smiley Face Killers" investigators: professor of criminal justice, Dr. Lee Gilbertson; and retired NYPD detectives Anthony Duarte and Mike Donovan say they’re trying to prove that these young men weren't just drunk and fell into a river and drowned.

On Wednesday’s episode of Dr. Phil, Gannon and his team share why they believe a group of individuals may be targeting these young, healthy, intelligent young men. Hear why they believe the victims were held for a period of time and killed before they were thrown in the water.

WATCH: Why Six Mothers Say They’re Convinced Their Sons Were Murdered And Did Not Die Accidentally As Classified

And on Wednesday, hear from six moms who say their sons died under mysterious circumstances – and why they don’t believe they accidentally drowned. Check here to see where you can watch.

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How Former Detectives Investigating 'Smiley Face' Murders Respond To Those Who Debunk Their Theories