The FBI said there is no proof that dozens of young men who died in mysterious drownings were actually murdered by a nefarious network dubbed the "Smiley Face Gang" — despite theories held by a group of retired detectives and victims' family members.
Former NYPD detectives Kevin Gannon and Anthony Duarte revealed their belief this week that the deaths of at least 40 different male victims — most of them white and college-aged — in about 10 states appear to be linked.
Among the commonalities, they say: The men's bodies typically were found in rivers and some of the scenes were marked with smiley-face graffiti. Gannon indicated that he and other investigators who have banded together in their own probe have substantial information connecting the deaths and pointing to homicide.
The FBI, however, doesn't believe the cases look like murders at the hands of the same serial-killing organization, nor does the bureau think the deaths are related or are even killings at all.
"Over the past several years, law enforcement and the FBI have received information about young, college-aged men who were found deceased in rivers in the Midwest," said Supervisory Special Agent Richard J. Kolko in a statement.
"To date, we have not developed any evidence to support links between those tragic deaths or any evidence substantiating the theory that these deaths are the work of a serial killer or killers. The vast majority of these instances appear to be alcohol-related drownings."
The bureau generally gets involved only when asked by local police — who also don't seem to be buying the idea that the young men didn't drown but were instead killed by smiley-face-painting gang members.
"We have no evidence to suggest otherwise, and no one has come forward with any evidence to suggest otherwise," said NYPD Deputy Commissioner Paul J. Browne in an e-mail to FOXNews.com.
Police departments usually record information about cases involving missing persons or unexplained deaths on an FBI-run database called ViCAP, which stands for the Violent Criminal Apprehension Program, according to the FBI. The reason: If similar cases crop up around the country, law enforcement will be flagged and can take a closer look to see whether they're related.
Among the victims the retired New York City detectives are attempting to link are University of Minnesota student Chris Jenkins — whose cause of death recently was changed to homicide — and Fordham University student Patrick McNeill.
Gannon and Duarte told reporters that the drownings seem to have been staged, especially since many victims were missing for months before their bodies turned up and some corpses looked like they had been tampered with.
Further, a smiley-face symbol was found painted at some of the drowning locations — in Ohio, Pennsylvania, Indiana, Wisconsin and Iowa.
Jenkins' body was discovered in the Mississippi River about four months after he disappeared in 2003. Police concluded he accidentally fell into the water and died after a night of drinking, but the retired detectives believe his death is suspicious in part because of how his body looked when it was found: encased in ice with his hands folded across his chest.
McNeill apparently drowned in New York City in 1997, also after bar-hopping. His body turned up in the East River. But his family refutes the notion that his death was an accident or a suicide.
Jenkins' family never believed similar theories about his death, either.
"We knew immediately that he would not be gone of his own volition," Jenkins' sister, Sara Lightner, told FOX News on Wednesday. "The minute he was missing, we knew something was desperately wrong."
Lightner said she has seen most of the data collected by Gannon and Duarte, but couldn't discuss specifics so as not to compromise the investigation.
"Kevin and Anthony have really strong facts to back everything they’re saying up," she said. "What they’re trying to do right now is to get the FBI to take a very close look at this and start making some arrests."
The FBI's Kolko said only that the bureau "will continue to work with local police in the affected areas to provide support as requested." There were no arrests afoot, however.
Gannon and Duarte did not respond to requests for further comment.
University of Baltimore criminologist Jeffrey Ian Ross warned against jumping to conclusions.
The idea that these were serial killings "may be a little bit premature based on the information released to the public," he said. "I don't understand how these kinds of deaths can be going on for at least a decade with nobody piecing them together."