A convicted killer who believed he was contacting young girls for sex has been jailed for public protection.

Lee Webster was caught out after he was led into a trap by paedophile hunters who created bogus profiles of young girls on social media.

Even after being confronted by one group in March and arrested he continued to offend in the same way.

The 31-year-old married father, who described himself as “a sad and lonely man”, was jailed for four-and-a-half years after admitting five offences of attempting to cause a girl to engage in sexual activity and two of attempting to cause a girl to watch a sexual act.

He will have to serve two thirds of the sentence before the parole board will consider his release.

Maidstone Crown Court heard Webster committed the offences from January to April this year.

Prosecutor Bridget Todd said personas of girls under 16 were created on Facebook by a group called Exposure Central.

Recorder Mark Weekes said the groups did work that was ordinarily done by the police, adding: “There is nothing wrong or improper about the way they conducted themselves.”

Webster was told by one of five girls he believed he was contacting she was 14, and he said he was 31 and from Dartford.

He asked her out for a meal and tried to arrange to meet her at Dartford railway station. He encouraged her to look at porn websites.

Miss Todd said Webster encouraged some of the “personas” to touch themselves and he sent one a picture of his private parts.

After the first arrest, Miss Todd said she was not able to state whether Webster was released on bail or whether the investigation was ongoing.

He “started again” in less than a month and was “surrounded” by another paedophile group called Shadow Hunters UK when he attended Darent Valley Hospital for a mental health appointment.

Webster, who has parted from his wife, told police he did not mean to meet any of the girls contacted.

He admitted: “I know I did what you say. I am really sorry. I feel I need help with my mental health.”

He has 20 previous convictions for 42 offences, including indecent exposure and arson with intent to endanger life.

Webster was jailed for five years in June 2013 for manslaughter and perverting the course of justice after he slipped 26 anti-depressant tablets into a friend's beer "for a joke".

He was sentenced to four-and-a-half years for killing Jason Wood and six months consecutive for perverting the course of justice by getting rid of the pill bottle which had contained Mirtazapine.

Mr Wood, 30, died in October 2012 within about three hours of swallowing the pills put into his beer can during a heavy drinking session at his flat in Camden Square in Ramsgate.

The court heard the combination of the pills, alcohol and sleep apnoea - which could cause Mr Wood to stop breathing - probably led to his death.

Philippa Beswick, defending in the latest case, said Webster’s mental health deteriorated and he had periods in psychiatric institutions.

“This is a man who engaged sexually with no fewer than five of what he thought were children" - Recorder Mark Weekes

He was released from his licence for the manslaughter offence in November last year. He was homeless and living rough in a tent in Dartford.

Recorder Weekes said: “This is a man who engaged sexually with no fewer than five of what he thought were children.”

“It seems abundantly clear you are attracted to young girls under 16,” he told Webster. “It is clear you had the intention to meet with those you thought you were talking to and take matters further.

“I unhesitatingly conclude you are dangerous within the meaning of the Act. You intended to meet and have sex with very young girls.

“It is an escalation in seriousness of your behaviour. You have a significant propensity to commit further offences.”

Webster’s name will appear on the sex offenders’ register indefinitely. A sexual harm prevention order was made and he will be barred from working with children and vulnerable adults.