Between 2005 and 2009, the bodies of eight women were found in swamps and canals surrounding  Jennings, Louisiana. Most of the bodies were found in such a state of decomposition as to make the actual cause of death difficult to determine.

The Jeff Davis 8, sometimes called the Jennings 8, refers to a series of unsolved murders in Jefferson Davis Parish, Louisiana.  

Suspect Zero  analyze Jack Unterweger, an Austrian serial killer who murdered Margaret Schafer in what appeared to be an isolated murder.  He was convicted in 1974 and was serving a life sentence when he once again used his manipulation to his advantage. He wasn’t finished with what he started and many would regret ever believing the mastermind behind this reign of terror.

Suspect Zero take a deep look into the Monster of Florence. Between 1974 and 1985, seven couples were murdered while having sex in parked cars in the hills of Florence, Italy.  

Suspect Zero  discuss David Parker Ray, AKA, “The Toy Box Killer."   Ray soundproofed a truck trailer which he called his "toy box", and equipped it with items used for sexual torture. He would kidnap between five and six girls a year, holding each of them captive for around three to four months. During this period he would sexually abuse his victims, sometimes involving his dog or his wife (who participated willingly in her husband's crimes), and often torture them with surgical instruments. Then Ray would either kill his victims or drug them with barbiturates in an attempt to erase their memories of what had happened before abandoning them by the side of the road. 

Suspect Zero  welcomes special guest, John Allore.  Since 2002, Theresa's brother, John Allore – whose podcast, Who Killed Theresa?– has continued the investigation, identifying 14 other unsolved murders from 1975 to 1981 which he believes may be connected. Beginning in 2018, John Allore started to focus on other Quebec cases from the 1970s through the present era, cases that further suggest systemic failures in how investigations are carried out.  They also talk about Luc Gregoire, a Canadian serial killer, who looks to be a viable suspect.

Suspect Zero  looks into the lesser known case of Michael Scott Magliolo, a nomad who would hitch rides with truckers to carry out his “quests” around Nashville, Ohio, and quite possibly other places that we are unaware of.

Suspect Zero will visit the 1972 cold case of Jeannette DePalma who went missing from her Springfield, NJ home.  Law enforcement authorities have denied that her murder was a result of Satanic rituals.  Further controversy was aroused when it was discovered that the body had been found on a cliff known to locals for several decades as, "The Devil's Teeth".

Suspect Zero will be discussing at the case of Mike DeBardeleben, a convicted kidnapper, rapist, counterfeiter, and suspected serial killer, who became known as the "mall passer" due to his practice of passing counterfeit bills in shopping malls bordering interstate highways across the United States.