Disturbing video shows serial killer explaining why he captured women and kept them as slaves

When we hear of extremely warped cases that stunned the world, it's safe to say we're often left with more questions than answers about what on earth possessed the culprit to do such a thing.

But it's not often that you get to see the perverted perpetrator provide a so-called explanation for their abhorrent crimes - even if it does make for a very disturbing watch.

Investigators, and later the general public, were able to delve inside the minds of serial killer Leonard Lake and his accomplice Charles Ng thanks to homemade video tapes the pair had recorded during their sick murder spree.

Lake had a long-running infatuation with lewd photography and pornography which dates back to his childhood, but his camera work took an even more chilling turn when he met his co-conspirator in 1980.

The California-born killer was enlisted in the United States Marine Corps in 1964 and went on to serve two tours of duty in the Vietnam War, which is when he was first diagnosed with schizoid personality disorder.

After experiencing what was described as a 'delusional breakdown', Lake received psychotherapy and was later medically discharged.

Some 15 years later, he met fellow former Marine, Ng, while working at a motel, with reports claiming that the pair first connected through an advertisement in a survivalist magazine which Lake had placed.

It marked the start of a sick and twisted relationship between the depraved duo, who turned a remote property in Wilseyville, northern California into a killing compound which they proudly described as their 'dungeon'.

Throughout the early 1980s, Lake and Ng raped, tortured and murdered between 11 and 25 victims at the rural cabin.

The pair mainly targeted women, but they were not scared of abducting entire families either - first killing the men and children, before holding the females hostage in a custom-built room in the bunker until they eventually murdered them too.

Lake and Ng would shoot the captives before disposing of their bodies by burying them in shallow graves on or near the property, or by burning the corpses and scattering the bones.

The serial killers recorded a series of home videos during their murder spree - including some which depicted the violent acts they were inflicting on their victims - which showed them chillingly discussing their reasoning behind the murders.

One particularly stomach-churning excerpt saw Lake describe his intentions for the women who tragically fell into his clutches and detailing how he would coerce his victims.

Take a look at this:

Laying back in an armchair, the 39-year-old said: "What I want is an off-the-shelf sex partner. I want to be able to use a woman, whenever and however I want.

"And when I'm tired or bored or not interested, I simply want to put her away. Lock her up in a little room, get her out of my sight, out of my life.

"A slave. There's no way around it. Primarily a sexual slave, but nonetheless a physical slave as well.

"I believe that I can, if I can, construct a holding cell, a place where I can put such a woman.

"A facility that is so stark and so empty, so cold, so quiet, so totally removed from the world, that I can quickly condition a young woman to cooperate with me fully."

The duo's sickening plot was only uncovered when police attended the cabin following reports of a theft, only for cops to find a foot poking out of the ground - before they then proceeded to dig up 18kg of burnt human bones.

Lake and Ng's known victims include Lake's brother, his best friend, his neighbours, various people met through newspaper advertisements, tenants of a boarding house where Lake had rented a room, a man who had advertised gay sex, and two of Ng's colleagues.

After being arrested on unrelated charges, police returned to the interrogation room to find Lake violently convulsing on the floor, while a brief suicide note was scrawled on a note pad.

The killer, 39, had swallowed cyanide pills that he had sewn into his clothes and never regained consciousness. He died on 6 June, 1985.

After discovering the graveyard of corpses at the cabin, police stumbled across Lake's handwritten journals and home videotapes. Ng was arrested a month later after shooting a security guard in Calgary, Canada.

He served four years for the attack and tried to fight his extradition back to the US, but was ultimately convicted of eleven of the twelve homicides - six men, three women, and two male infants - by a court in the States in February 1999.

Despite him insisting he was merely an observer to Lake's heinous crimes, he was sentenced to death.

Ng, now 63, remains on death row at San Quentin State Prison.

The last execution in the state of California was in 2006.