Cox’s name is still missing from Missouri’s sex offender registry. He’s also not listed in the Colorado database, where he was convicted in 2003 for his role in an international online child pornography ring. And he’s not part of the national database.

Cox is incarcerated in North Carolina as a “sexually dangerous person,” a classification created by the 2016 Adam Walsh Act to give the government the power to keep people confined beyond their sentences if they are deemed highly likely to re-offend. He was certified as he neared the end of a 10-year sentence for his role in an international child pornography ring.

Major Case Squad

Robert Lowery Jr. was a police officer in Florissant when his father, one of the founders of the Major Case Squad of St. Louis, tapped the son to lead the Housman case. The absence of a registry forced detectives to create lists manually, he recalled.

Lowery said those who would know the criteria for those lists have died.

“I can assure you that the (suspects) we were aware of were all found, and an extensive amount of work went into trying to tie them to the case or eliminate them,” he said. “I’ve always said, ‘What frightens me is the ones who weren’t on that list.’”