Although Charles Cullen has been confirmed of killing 29-35 people, authorities think his victim count might be in the hundreds.

Luis Garavito became known as "The Beast," after he murdered 138 young children in Columbia, but is it possible he will barely serve any time behind bars for his crimes?

Randy Steven Kraft terrorized California, murdering over 50 young men over a 12 year period. But how did police finally capture the "Scorecard Killer," and did he do it alone?

In 2016, Lonnie Franklin Jr., was convicted of 10 murders and one attempted murder, and was sentenced to death. But did Lonnie Franklin Jr., really take a fourteen year break in the middle of his killing spree?

Gerald and Charlene became known as "The Love Slave Killers," after terrorizing California and killing 10 people - but was it nature or nurture that drove this couple to kill?

One of the most prolific women serial killers in United States history, Delphine LaLaurie, has been portrayed in pop culture for decades for her brutal torture and murder of slaves. But what is the truth behind LaLaurie, and was it nature or nurture that drove her to kill?

NOTE: English translations of a copper plate found in a cemetary state that LaLaurie died in 1842, while French archives note that she passed in 1849.