Actor Billy Baldwin disclosed his bizarre connection to the suspect charged in the unsolved Gilgo Beach murders on Long Island, in a candid post to his social media.
"Shocked to learn this morning that the Gilgo Beach serial killer suspect was my high school classmate Rex Heuermann," the 60-year-old wrote.
The men attended Berner High School in Massapequa, New York – both graduates of the class of 1981.
"Mind-boggling," Baldwin wrote. "Massapequa is in shock."
"23andMe strikes again," the "Gossip Girl" actor continued in his caption.
One user asked Baldwin to expand, interested in what a reference to the popular genetic testing service meant in connection to the case.
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He wrote back, "When people allow their 23 and me DNA results to be posted publicly it can often resolve a cold case crime or paternity issue because they can link someones (sic) child or niece or nephew to a suspect by their 23 and me results."
Police previously shared that they were able to match DNA from a pizza Heuermann ate to genetic material found on a woman’s remains, which led to his arrest on Thursday.
On Friday Heuermann was charged with murder in the deaths of three of the 11 victims in a slew of unsolved deaths from over a decade ago. Police have stated in the past that it's unlikely one person was responsible for all the deaths.
The Long Island architect, who is married with two children, has lived for decades across a bay from where the remains were found in 2010 and 2011.
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The famous Baldwin brothers – Alec, Daniel, Billy and Stephen – all grew up in the Long Island community and attended the same high school as the suspect, 59.
Representatives for the Baldwin men did not immediately respond to Fox News Digital's request for comment.