The Fishmongers’ Hall attacker was an “influential” inmate who associated with Fusilier Lee Rigby’s killer before his release, an inquest has heard.

Convicted terrorist Usman Khan, 28, spent eight years in prison where he was involved in a string of violent incidents and “extremist bullying”, the inquest jury at London’s Guildhall was told.

Eleven months after his release, Khan killed Cambridge graduates Jack Merritt, 25, and Saskia Jones, 23, at a Learning Together prisoners’ educational event at Fishmongers’ Hall in London.

On Tuesday, senior investigating officer Detective Chief Inspector Dan Brown gave evidence about Khan’s life and long history of extremism in and out of prison.

Born in Stoke-on-Trent to parents who had come to the UK from Pakistan, he was described by a former teacher as having a “chip on his shoulder” and “teenage swagger”.

At the age of 13, Khan was excluded from school after assaulting another pupil and exchanging racial slurs, for which he was given a youth reprimand, the court heard.

The court heard how Khan was attracted to extreme Islam in his teens and took an interest in prominent figures Anwar Al-Awlaki and Anjem Choudary, the leader of terrorist organisation al-Muhajiroun (ALM).

In 2008, he preached in Stoke on behalf of ALM and police raided the address where he was living, jurors heard.

Afterwards, Khan said he was born and bred in Stoke, and insisted: “I ain’t no terrorist.”

But within years, Khan was one of nine men from London, Stoke and Cardiff to be convicted of terrorism offences.

In December 2010, Khan discussed with another male how to construct the pipe bomb from a recipe in the al Qaida magazine Inspire, jurors heard.

Khan pleaded guilty to engaging in conduct in preparation of terrorist acts and was in custody until the end of 2018.

In a basis of plea, Khan admitted plotting to set up a terrorist training camp in Pakistan which might send fighters back to the UK.

In February 2012, Khan was handed an indeterminate sentence which was varied upon appeal to an extended sentence.

It meant Khan had to serve eight years in custody but no longer needed the approval of the Parole Board before his release, the court heard.

Jurors were told how Khan became a senior figure amongst extremists in prison and was categorised as a “high risk”.

He was involved with violent incidents and radicalisation of fellow inmates during his time at seven prisons across England.

In January 2011, Khan suggested he had access to a weapon and would “do someone in the eye or neck” and wanted to die and go to paradise, jurors heard.

In March 2011, Khan and others were involved in an attack on another prisoner to shouts of “Allahu Akbar”, Mr Brown said.

The same year, Khan shouted during the two-minute silence for Armistice Day.

In June 2012, Khan recited a poem which included the line “cut off the kuffar’s head”, the court heard.

In May 2013, a stockpile of chemicals was found in Khan’s cell which would not have been capable of making an IED but was still “very concerning”, Mr Brown said.

In November of that year, a Church of England chaplain was caught up in an assault by Khan on another prisoner.

The same day, a razor blade was found in his cell, the court heard.

In 2017, while at HMP Whitemoor, Khan remained a high risk, Mr Brown said.

While his behaviour was noted as “acceptable” with “no recent adjudications”, evidence suggested he continued to harbour extremist attitudes and deliberately “told lies or ticked boxes to achieve progression”.

In March 2017, Khan talked about his Muslim faith with Michael Adebowale, who beheaded Fusilier Rigby, jurors heard.

By June of that year, Khan was regarded as an “influential” terrorist prisoner involved in “extremist bullying”, Mr Brown said.

In October 2018, intelligence on Khan suggested he would “return to his old ways”.

Meanwhile, he was said to have engaged “positively” with Learning Together, jurors heard.

The inquest into the deaths of Ms Jones and Mr Merritt continues.

Read more: Prison chaplain: I may have been ‘conned’ by ‘remorseful’ Fishmongers’ attacker

One of Lee Rigby’s killers is reportedly fighting for life after catching coronavirus.

Michael Adebowale is serving a life sentence for murdering Fusilier Rigby in May 2013 on the streets of Woolwich, south-east London.

The Sun reported that the 29-year-old Islamic terrorist was removed from Broadmoor last week following a deterioration in his condition after he contracted Covid-19.

Adebowale and Michael Adebolajo ran over the 25-year-old soldier close to Woolwich Barracks in May 2013 before stabbing him to death in broad daylight.

The father-of-one died as a result of multiple cut and stab wounds after the attack fuelled by Adebowale and Adebolajo’s extremist beliefs, described as a “betrayal of Islam” at their murder trial in 2014.

Read more: Lee Rigby murder: Murdered soldier is not forgotten, says army colleagues

Paying more attention to substance abuse could predict or prevent radicalisation, a study has concluded.

The research suggested terror attacks are carried out by “psychologically disturbed young men” who sought out radicalism as a form of self-help.

According to the findings, the attackers had a history of violence due to substance abuse, had acted alone, had no help from a radical group and died as a result of their actions.

The study, conducted by international security lecturer Dr Lewis Herrington from Loughborough University, looked at six incidents – including the Westminster Bridge attack by Khalid Masood in 2017, and the murder of soldier Lee Rigby in 2013 by Michael Adebowale and Michael Adebolajo.

Dr Herrington found that paying closer attention to Masood’s regular cocaine and alcohol use, Adebolajo and Adebowale’s chronic drug use, and Berlin Market attacker Anis Amri’s alcohol consumption since the age of 13, could have provided intelligence services with “helpful indicators” to prevent the attacks.

The study concluded that from a population of 52 lone-actor terrorists across Europe between 2012 and 2017, at least 75% had a history of chronic substance abuse.

Research also found that Muslim communities which introduce the 12-step recovery programme for addiction could help prevent vulnerable members seeking Islamic fundamentalism.

Dr Herrington said: “Fundamentalism provides a structurally equivalent means of recovery from addiction as the widely recognised 12-step programme.

“However, it is a programme that inadvertently directs a minority of vulnerable men along a pathway towards isolation, obsession, resentment and finally martyrdom, rather than sobriety.

“Based on our understanding of addiction, isolation leads to extreme feelings of self-pity, guilt, shame and remorse.”

Dr Herrington continued: “This in turn may trigger suicidal thoughts within Islamic fundamentalists who are unable to commit suicide due to newly established religious beliefs.

“Our six case studies were not exceptional, and some attacks may have been prevented if the perpetrators had been screened for addiction.

“The case of Khalid Masood is especially alarming, and there are almost certainly many others like him.”

He added: “Improved knowledge of the connectivity between addiction and suicide terrorism may provide us with a new working framework within which to help prevent future attacks.”