Studying the signature.
Season three of Oxygen's Mark of a Killer—the true crime series that follows the story of investigations guided by a murderer's postmortem signature—is finally back, and judging by this exclusive sneak peek of Sunday, Oct. 17's all-new episode, you won't want to miss it.
The year is 1983, and authorities in both Illinois and Indiana are noticing an alarming pattern: young men are being stabbed to death, with their bodies all abandoned in remote areas, covered in brush and left with their pants pulled down.
As one Illinois investigator explains in the preview, which you can watch in the below clip, "We contacted detectives from Indiana and we decided to hold a meeting with all the jurisdictions involved to try to piece together, 'Are these all connected or not?'"
Examining homicide cases in both states from 1982 through August of 1983, it didn't take long for the law enforcement officials to get their answer.
Not only had many of the victims' bodies been dumped off major interstates or highways, but they also shared an extremely similar cause of death.
"You could take a silhouette of a body and then put plastic overlays with all the different stab wounds on them and every one of them would almost match up perfectly," the Illinois investigator reveals.
The brand new Mark of a Killer will feature additional first-hand accounts from detectives who worked on the cases, as well as interviews with criminal psychology experts and family members and friends of the victims.
Tune in to the episode on Sunday, Oct. 17 at 7 p.m., only on Oxygen.
(E! and Oxygen are both part of the NBCUniversal family.)