Glenda Cleveland died 12 years ago after long battle for justice against Jeffrey Dahmer

Glenda Cleveland, Jeffrey Dahmer's neighbour, died 12 years ago after tirelessly battling for justice against him.

Check out the trailer for the spine-tingling series here:

And that's just one instance of the real-life efforts of Cleveland, who repeatedly contacted the FBI and police to no avail - had she been taken seriously, five of Dahmer's victims could've been saved.

Despite the unsettling scenes, it's hard to look away from Ryan Murphy's latest creation, and our only bit of solace comes from Cleveland, who had raised the alarm about Dahmer months before he was caught.

So, who was Cleveland?

Cleveland had lived in a building near the infamous killer and tried to warn police several times about his concerning behaviour.

In the second episode of the new series, Cleveland's daughter and niece spot a drugged and bloody 14-year-old Konerak Sinthasomphone (Kieran Tamondong) leaving Dahmer's apartment.

Of course, Cleveland is quick to alert the police, but they buy into Dahmer's cover-up story that the young boy is his boyfriend, and they were just having a fight.

The police let Dahmer take the young boy back to his apartment, which proves fatal to him.

Later that night, Cleveland would call the police, asking, insisting even, for police to check that the child with Dahmer was okay.

Sinthasomphone's missing poster would be hung in the streets a few days later.

Five of Dahmer's killings occurred after Cleveland had tried to alert police, as well as the FBI.

Dahmer was eventually caught on 22 July 1991, when Tracy Edwards escaped his horror-filled apartment.

Edwards flagged down police, two different officers from the incident with Sinthasomphone, who soon found severed heads and dismembered body parts in the apartment. 

Following Dahmer's arrest, Cleveland stayed put in her apartment. She was honoured by the Common Council, and the County Board, and was called a model Citizen by Mayor of Milwaukee, John Norquist.

However, many were outraged that Cleveland was ignored, including famous Reverend Jesse Jackson, who berated police for believing Dahmer over Cleveland.

“Police chose the word of a killer over an innocent woman," Jackson said.

Cleveland continued to live in the apartment neat Dahmer's infamous residence until 2009 - she died on December 24, 2010, of natural causes.

Monster: The Jeffrey Dahmer Story is available to watch now