Sky's new true crime documentary series examines a very sinister murder theory

Six deaths that appear to be linked. True crime fans will definitely be watching this on Sunday.

With a plethora of documentaries to look forward to in 2020 - we're previewed the most interesting ones here - it appears that fans of the genre will have plenty to get stuck into over the coming months.

However, one feature that definitely piqued our interest is The Smiley Face Killers: The Hunt for Justice and it starts this Sunday.

Ok, so what's it about?

Retired detectives Anthony Duarte and Kevin Gannon investigate six deaths - all linked by the victims' ages, cause of death and the fact that smiley face graffiti was found at most of the crime scenes.

The smiley face murder theory proposes that a number of young men found dead in the water across several American states did not accidentally drown, as concluded by law enforcement agencies, but were victims of a serial killer, or serial killers.

The series follows an active private investigation that's spearheaded by the retired detectives as they work with the victims’ families and top forensic experts.

The aim of the documentary series is to further investigate and question whether these mysterious drownings aren’t accidents, but homicides.

Hanging over the investigation is the one big question, could all of these deaths be connected to the larger theory of the smiley face killers?

It's worth noting that before they presented these cases in the documentary, the two detectives, along with their investigative partners, had their theories about the so-called serial killer cell debunked.

In 2008, the FBI examined the deaths and concluded that the vast majority of the deaths were accidental drownings, as previously stated in the case reports.

In 2012, the Center for Homicide Research looked at 40 deaths and came to the same conclusion.

Meanwhile, despite their steadfast investigations picking up where local law enforcement left off, the various police departments and medical examiner offices in all but one case have refused to change their conclusions.

However, mystery still surrounds these deaths.

In terms of its aesthetic approach, the six episodes each focus on one victim.

During the course of each episode, viewers will be presented with information on the case and learn how the smiley face murder theory may apply to the case, and the outcome of the investigation.

The official synopsis states: "Since 1997, more than 350 college aged men have died in accidental drownings in the US. The bodies have all been found in regional clusters around the country with the victims being eerily similar: all top students and athletes who disappear after a night out drinking with friends.

"To add to the mystery, found in the vicinity of almost every dead body is a graffiti-style mark of a smiley face. This docuseries follows a unique team of former NYPD investigators who have dedicated their lives to proving the country’s most notorious string of mysterious, accidental drownings, aren’t accidents at all.

"Will they be able to prove that these deaths are actually homicides committed by one of the most prolific serial killers in US history?"

The first two parts of The Smiley Face Killers: The Hunt for Justice air on Sunday 26 January at 9pm on Sky Crime and NOW TV.

Take a look at what's in store.

Clip via Oxygen