A man accused of murdering a gay supermarket worker embarked on a campaign against uncaught paedophiles using “military strategy” to track them down after overhearing convicted prisoners planning new offences while in prison, a court heard.

Christopher Hunnisett, who is on trial accused of killing supermarket worker Peter Bick, told the court he used the internet and a network of “live sources” – some made in prison – to investigate rumours of child abuse.

He assigned possible offenders militaristic “call signs” depending on the strength of evidence against them, he said.

The jury at Lewes Crown Court was told Hunnisett, 28, started the operation after being acquitted and freed in September 2010 following a retrial for the murder of the Rev Ronald Glazebrook, whom he accused of abusing him, for which he had already served nine years of a life sentence.

While on remand ahead of the second trial, the court heard today, he took part in “therapy sessions” at Grendon Underwood prison in Buckinghamshire, designed as a form of restorative justice to try to treat sex offenders. But he overheard offenders planning a paedophile ring.

Hunnisett told the court today he investigated Bick, 57, after being told a “rumour” about him, saying the police lacked enough power to catch paedophiles.

Giving evidence, he told the court that after “philosophy” discussions with other prisoners on how to deal with sex offenders, he decided he wanted to track down “rapists, paedophiles, those who force women into prostitution, sex traffickers” by breaking the law and hacking into profiles on sex websites to see what users were doing – something he claimed the police cannot do.

“There are so many paedophiles in this country, over 600,000 who just offend against children,” he said.

“Even if I stopped more than 100 a day I would take over 20 years to deal with them. It is impossible for one person to stop them all.

“I commend the police and the child protection agencies for what they are doing but they are beaten by certain rules and regulations.

“If you really want to find out … you have to look at their (website) profiles and see who they are talking to. It is not hard to find these people but the police are beaten by the rules.”

While in the witness box Hunnisett used military terms like “in the field” to describe how he investigated claims of sex offending, using call signs like “Sierra” to describe a “suspect” and “Tango” to describe a “target” against whom he had proof of illegal activities.

One they had been “dealt with” they were reclassified as “x-ray”.

He admitted reading books about intelligence agencies to help him plan his activities.

He said he tracked down Bick after a contact gave him the name of a “Peter” living in Bexhill, showed him a digital picture and told him a “rumour” of what he was alleged to have done.

Hunnisett said he investigated and met several men called Peter before he found Mr Bick.

Mr Bick was killed during the early hours of January 11 last year after Hunnisett, whom he had met for sex, inflicted five severe blows to his head with a hammer and strangled him with a shoelace, the court has been told previously.

The jury has also heard that Hunnisett wrote to his girlfriend, Lucy Anderson, while on remand, admitting the killing.

It read: “I know you do not understand why I did what I did. In short, I simply wanted to stop some really nasty people hurting kids, the young, the weak, the vulnerable.

“I never planned to hurt him, I just wanted to stop him, get evidence on him to get him to confess and tell people what he was.”

Hunnisett went on to tell Miss Anderson that when Mr Bick confessed to him he lost control, the court heard.

He added: “You have no idea how mad it makes me knowing that someone can do that and they think it’s okay.

“It’s disgusting and they have no idea how much it destroys a person and damages them, and no one gives a damn about it.”

The trial has already heard there is no evidence that Mr Bick was a paedophile.

Hunnisett, of Chanctonbury Drive, Hastings, East Sussex, denies murder but admits manslaughter by way of diminished responsibility.

Hunnisett told the court how he killed Mr Bick while “interrogating” him using techniques that were “the same sort of thing as waterboarding” – before leaving to watch another potential target.

He said he had his body extensively tattooed with symbols of his “moral code” while inprison and his plan with each target was to gain enough evidence to allow the police to arrest them and have them imprisoned “for ever”.

He said he had contacted Mr Bick via a website and met him at his flat, where he claimed the older man had admitted committing sex acts with youths aged 14 and 16.

He then attempted to “honeytrap” him, claiming he could arrange a threesome with himself and a public schoolboy aged 15, whom he invented using the online alias “Golden Boy”, while the boy’s parents were away on holiday.

He claimed Mr Bick agreed but before it was due to happen he travelled to Bexhill, where he told him the boy was unable to join them.

Hunnisett said he then stripped naked and committed a sex act while Mr Bick watched, claiming it was part of his cover. Under the pretext of sex games he then tied the also naked Mr Bick to his bed with shoelaces tied around his neck, saying the older man had admitted it was something he had done with one of the young boys.

But as soon as Mr Bick was restrained Hunnisett began to use force, grabbing a camera and ordering Mr Bick to make a videotape confession of his alleged crimes, which Hunnisett claimed he did.

“I think he thought I was going to blackmail him with the information,” he said.

“When I told him I was going to expose him, that is when he started to struggle and he got his hand free and got me by the throat around the neck.

“With his other hand he reached for a box on the (bedside) table. He then went to grab the hammer that was there but he was restricted by the neck lace.

“He was able to grasp it by his fingertips and I was able to wrench it from his hand.

“I hit him once to get his hand off me but it got tighter. I hit him three, maybe four times after that.”

He said the man “was probably dead after the first blow” but he tried to undo the shoelace when he slumped forward and it started to choke him.

After the killing Hunnisett told the court he thought about committing suicide but decided against it. He said he washed Mr Bick’s body and spent three or four hours “proving” the flat, scouring it for evidence of sex crimes, which he claimed he found.

He said he destroyed electronic equipment, including laptops and memory sticks with the evidence on, but left the body surrounded by items he hoped would lead police to work out why Mr Bick had been killed.

He then stole Mr Bick’s car and disposed of seven bags of stolen material, including the hammer, in remote locations. He then drove to another target, named in court only as Mr A, whom he suspected of sex attacks on girls, to watch his home.

The trial continues.