Executed by the State of Illinois in 1994 for murdering 33 teenage boys and young men between 1972 and 1978, serial killer John Wayne Gacy is long gone.

But rumors about the possibility of more Gacy victims live on.

That’s why a retired police detective, a filmmaker, and a veteran journalist are now fighting to reopen the Gacy investigation by searching a property where the notorious serial killer may have buried additional bodies. Their argument is not that anyone in law enforcement needs more murders to solve. Instead, they say, it may be possible to identify the remains of people who disappeared between 1972 and 1978. Those cases remain cold, and Gacy may have been responsible for more killings than anyone wants to admit.

At the heart of their fight is whether noninvasive, ground-penetrating radar can confirm or deny — without a shadow of doubt — the existence of a clandestine grave site. An infrared technician who recently surveyed the Chicago property told me it can’t. “No technology is 100 percent,” he said. But there may be more at play here. Politicians and powerful governmental employees can confirm or deny, too. And, in this case, a sheriff's office may be pushing hard to keep any remaining evidence in the Gacy case underground forever.