Dr. Al Carlisle made breakthroughs in the field of criminal psychology by working closely with the exact subjects he was studying. He’d spend hours and hours interviewing murderers and rapists in his quest to understand the criminal mind, resulting in him coining the term “compartmentalization.”

But it was Carlisle’s collaboration with Dr. Katherine Ramsland, a professor in criminal psychology at DeSales University, that led to the term “cubing” — which BTK Killer Dennis Rader actually came up with.

As Ramsland explained during a 2023 CrimeCon panel on the Oxygen True Crime show Violent Minds: Killers on Tape — during which clinical psychologist Dr. Gary Brucato and the show’s executive producer Kathryn Vaughn also spoke — she and Carlisle wanted to see what Rader would think of his assessment of Ted Bundy, so she gave him access to Carlisle’s papers. While Rader “didn’t always respond positively to other people’s theories,” the serial killer was impressed by Carlisle’s understanding of Bundy. Specifically, Rader affirmed Carlisle’s theory that Bundy was able to “compartmentalize” different parts of himself to avoid notice.

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But then, Rader took the theory a bit further. He suggested that compartmentalization wasn’t the best way to understand how killers are able to live among the general public undetected. In his mind, the phrase “cubing” made more sense because it represented the “different faces of a person.”

“He can be what he needs to be. He just twists the cube around,” Ramsland explained.

As for how Carlisle felt about Rader’s criticism, Ramsland said, “Al Carlisle responded well to that.”

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Though many individuals would question why Ramsland or Carlisle would trust a killer’s word, Ramsland said these overly confident killers offer criminologists rare insights into the mind of a criminal.  “You want subjects who want to be known; who think they’re interesting enough,” she shared.

Brucato added that sometimes these killers simply want to reassert their confidence after being caught. Or, as he put it, “For a lot of these people, it’s about leveling the playing field after they’ve been toppled.”

This was likely the case for child killer Manny Cortez, whose killings of two young girls are covered on Oxygen’s Violent Minds: Killers on Tape. Ramsland and Brucato discussed Cortez at length, particularly his decision to target children. Brucato theorized that Cortez had been embarrassed at a young age and wanted to overpower the same age group that had made him feel inferior.

“It speaks to his control needs and the fact that even an adult victim was not enough for how he wanted to feel better than,” Brucato continued.

To learn more about Cortez and his crimes, watch Violent Minds: Killers on Tape, streaming now on Peacock.

CrimeCon 2023 is produced by Red Seat Ventures and presented by Oxygen True Crime.