The chilling story of the murderer who strangled his cellmate using a pair of socks because he was desperate to be executed

YOU'D think being sentenced to death would be terrifying - but murderer James Robertson was ecstatic when he heard that he would finally be executed for his crimes.

Robertson, a long-term prisoner, was sentenced to death in 2012 for murdering his cellmate, while already in a Florida jail for a string of robberies and assaults.

The 54-year-old has yet to be executed, and is now appearing on new documentary series I Am A Killer, where he talks candidly about his fight to earn the death penalty.

He looks like a TV villain, with a smooth shaven head and a wide smile with missing teeth.

And he is so relaxed about his sentence that he doesn't really mind whether it comes as a result of electrocution or lethal injection.

"I'd much rather have a needle stuck in me than be electrocuted but I could go either way," he says on the show, speaking in a deep southern accent. "You read how it's 'inhumane' but that's a load of bulls**t. You don't feel anything."

A reputation for violence

Looking at him with his hands cuffed in his lap and his eyes twitching, it would be natural to dismiss Robertson's death wish as a result of madness.

But the chilling truth is that he knows exactly what he's doing - and he's been deemed medically sane as part of his trial.

Robertson - AKA death row prisoner #322534 - has been behind bars for 37 years already, serving a sentence of over 100 years.

He was just 17 when he was found guilty of his first major crime - trying to rob a local shop to fund his cannabis habit, when he was caught in the act by a pair of security guards.

Robertson was arrested and given 10 years in jail for burglary, aggravated assault and his attempt to resist arrest.

But while he was inside Charlotte County prison, Robertson earned a greater reputation for violence, smuggling a knife into his cell and using it remorselessly in his many arguments with other inmates.

The brawler added years to his sentence with every stabbing, riot, and assault he carried out behind bars, and ended up facing a century in prison.

He was also transferred to "close management" - solitary confinement - where the most dangerous inmates are cooped up on their own for 23 hours a day, separated from the general population with fewer privileges and no company.

Desperate to die

When he asked to be transferred back to the general population, Robertson's enormous rap sheet was held against him.

"You just lose all motivation," he says. "The guards humiliate you all the time and treat you like you're a bug.

"You're sat in that cell all day. It's inhumane."

It seems that the prospect of a life in solitary confinement was too much for Robertson to bear, and he decided he'd rather be dead.

He says: "Finally, I got mad and said 'I'm going to go ahead and kill somebody.' It was premeditated. I wanted to get on death row."

Robertson wanted a permanent change of scenery, and in 2008 his opportunity came.

The repeat offender was moved into a shared cell with Frank Hart, a middle-aged man jailed for committing lewd acts in the presence of a child.

"I felt pretty confident I could overpower him," Robertson says. "And I didn't want to have a child molester in my cell. "

Night fell, and Robertson worked out that the 25 minute window between the guards' rounds gave him an opportunity to pounce.

He tied together a pair of socks and nudged his cellmate awake, before leaping onto his bed and looping the homemade garrote around Hart's skinny neck.

There was a five-minute struggle, and then Hart stopped gasping for air and fell limp back onto the bed.

"I don't feel bad about it," says Robertson, breaking into a morbid, hearty laugh.

Life on death row

In 2009, Robertson was charged with Hart's murder, but the death penalty wasn't on the table as a punishment and his attorney refused to ask for it.

Outraged, the killer hired a new lawyer and demanded execution - starting a landmark, three-year legal battle which ended with him being sentenced to death in 2012.

In the years since Robertson was first jailed, grey hairs have started knotting in his beard, and deep lines have appeared beneath his eyes.

He told his lawyers that he was so set on dying sooner rather than later because of this - he's getting on now and he doesn't want to grow old in prison.

Having spent his life tormenting the vulnerable people around him, Robertson worried that, before long, he would become a target himself.

A prison nurse also explains in the show that death row is widely considered to be cushier than close management, where Robertson had spent the past few miserable years.

For a lonely, sun-starved man with no entertainment or company, the appeal of a ward with better food, TVs and a greater sense of camaraderie was obvious.

"I just got to the point where I said: 'f*** this - I'm going on death row," Robertson says.

But while he may have finally made it there, he's not dead yet.

He still doesn't have an execution date, and there could still be years standing between him and a lethal injection.

"I'm not angry or bitter," he says. "That's life and I accept full responsibility for the way my life turned out.

"I'm ready to go. It's over. But there's a long list on death row so I don't know how long I'll be waiting."

Previously, we shared the story of the murderer who was dragged to his execution cell and then saved with just moments to spare.

I AM A KILLER airs Tuesdays, 9pm on Crime + Investigation.