The moment a killer returns to the crime site and boasts to police that he "knows what happened," there is captured on a horrifying body cam video that has recently been made public.

Marek Hecko, 26, stabbed Adrian Ellingford, 44, twice in the back at a Chelmsford house just hours before the video was recorded.

When police arrived at the scene of the attack on July 25 last year, they discovered Ellingford with two stab wounds, one so severe that it had fractured and sliced a bone in his chest.

According to a statement released by Essex Police, a 'heavily intoxicated' Hecko, who was 'carrying a bottle of brandy,' approached the officers on scene duty at the residence on Nelson Grove.

He continually informs the police that he "knows what happened" and "can help," as shown in the video.

He replies, "I'm not going to tell you my name because I don't give a f**k... because I know what happened," when they ask him for his name.

"And you need me to figure out what happened. If you don't have me, you don't know what happened."

Hecko claimed to have witnessed another man enter the home and assault Ellingford in a different video.

"I don't know what happened," he added. "He just got f***ed up."

The officer was then the target of his increasingly hostile behavior as he told her, "This city's f***ing mine."

Hecko was detained and recognized as the primary suspect after being immediately arrested.

The 26-year-old was charged with murder within a short period of time and stayed in detention after investigating hundreds of avenues of inquiry.

Hecko attempted to make the case that he went to the address after witnessing what happened on the news during the trial, which was underway on February 13 at Chelmsford Crown Court.

Unfortunately, there was no news or information available on social media.

Hecko's previous partner, who was with Ellingford the night of his murder, was the target of stalker behavior, the court heard.

The jury returned a verdict of guilty of murder in less than a day.

Hecko was given a life sentence on Tuesday, March 14, with a minimum of 26 years.

In court, Ellingford's wife gave an impact statement, detailing how he was an "amazing husband, loving son, a caring brother, a friend to many and most importantly a truly brilliant father."

Detective Chief Inspector Louise Metcalfe said: "From the moment this was declared a murder investigation, our team worked tirelessly to gather CCTV statements and compile the evidence needed to charge Hecko."

"Despite the huge amount of work going on behind the scenes, we prioritized supporting Adrian's family, and our family liaison officers have done an incredible job from the start."

"This was a senseless attack on Adrian, which has left two children without a father."

"I hope that they can move forward and find some closure now that Hecko is behind bars."