The failure to identify the deception of a man who murdered a woman after being released from a mental health hospital “could happen again” in other cases, an inquest into her death has heard.

Theodore Johnson murdered 51-year-old Angela Best at his his home in Dartmouth Park Hill, Tufnell Park, on December 15 2016 after she ended their 20-year relationship and met another man.

He beat and strangled her after she went to his flat to help him with a passport application.

Ham & High: Murderer: Theodore Johnson. Picture: Met PoliceMurderer: Theodore Johnson. Picture: Met Police (Image: Archant)

He was sentenced to life imprisonment in 2018 when he admitted murder.

Johnson had two previous manslaughter convictions after killing his wife in 1981 and another former partner in 1992.

But he spent fewer than five years in a secure hospital before he was let out in October 1997 on condition he tell supervising doctors and social workers if he formed any new relationships - which he repeatedly failed to do, even though he had already been seeing Ms Best for a year.

Dr Shamir Patel, clinical director of specialist services at Barnet, Enfield and Haringey Mental Health NHS Trust, spoke at St Pancras Coroner’s Court today (June 3) to outline the steps taken to release patients.

In September 1994, Johnson was allowed out of a psychiatric unit for the first time on escorted community parole.

In mid-1995, he was given unescorted leave to spend two days a week at a City and Guilds course on furniture restoration. It was there that he met Ms Best the following year, after she moved to Tottenham from Manchester.

Johnson denied being in a relationship on multiple occasions in the years after his release.

Asked by coroner Mary Hassell if it had been realistic to rely on Johnson’s self-assessment, Dr Patel replied: “In this case it was unrealistic as there had clearly been a level of deception over a period of time.”

It was also heard that there were just two unannounced visits to Johnson’s flat.

Dr Patel, who did not oversee the facility at the time of Johnson’s release in 1997, said: “Certain things we can do and certain things we can’t.

“In terms of mental health specifically, we are not in a position to break doors and arrive unannounced.

“Unannounced visits aren’t common. They’re considered quite intrusive.”

He said such visits could “induce stress” in former patients and risk their “mental state deteriorating”.

Dr Patel said that mental health workers “rely on what patients tell” them to make judgments.

The coroner asked if it is still possible for them to be deceived by a mental health patient.

Dr Patel replied: “I can’t suggest it won’t happen again.

"It could happen again.

"I wouldn’t be comfortable in suggesting it couldn’t happen again at all.”

He said that had Johnson been released now, a multi-agency approach would be taken to check his relationships.

But Dr Patel added: “Would that uncover the events that transpired? That’s under question.

“There’s a potential that it could still happen.

"There would have to be clear suspicion that Johnson was in a relationship to justify any action.”

Ms Best was beaten with a claw hammer and strangled with a dressing gown cord after she went to Johnson’s flat to help him with a passport application.

Health workers described him as someone with “a lack of remorse and lack of empathy”, adding that he was “quite shallow and manipulative”, the inquest heard.

However he was not described as a “pathological liar”.

In a witness statement from April 2017, read out by the coroner, Johnson was “not believed to have a female” at his address during visits which had been planned with his knowledge.

In 2018 Johnson was jailed for life at the Old Bailey and ordered to serve at least 26 years for Ms Best’s murder.

His sentence was later increased to 30 years.

The inquest, attended virtually by counsel and family members, is expected to conclude on this afternoon (June 3).

Last week the inquest heard how Ms Best's sister is “extremely angry” her sibling was not protected.