The sister of the third victim of a serial killer who killed his partners is “extremely angry” her sibling was not protected, an inquest heard.

Theodore Johnson brutally murdered 51-year-old Angela Best at 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.

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 1993 - but in 1997 he applied for a conditional discharge from the hospital order imposed as part of the 1993 conviction.

One of the conditions was to alert authorities to any relationship with a woman - which he failed to comply with for years.

Ms Best’s sister Lorraine Jones said the family was “inconsolable” after what happened.

In a statement read out by Coroner Mary Hassell at the inquest into Ms Best’s death at St Pancras Coroner’s Court, Ms Jones said: “I feel extremely angry because my sister was not protected.”

She complained about missed opportunities, described a “severe lack of professional curiosity” and referred to a “lack of supervision and accountability”.

Johnson repeatedly lied to authorities who were monitoring him in the community.

In 1981, he was was found guilty by reason of “provocation” of killing his wife Yvonne Johnson by pushing her off the ninth-floor balcony of their home in Wolverhampton.

Then, in 1993, a couple of years before meeting Ms Best, he was convicted of strangling his common law wife Yvonne Bennett with a belt at their home in London, before trying to hang himself.

The prosecution accepted his responsibility was diminished due to depression and a personality disorder and he was handed a hospital order with restrictions at the Old Bailey.

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

Then in mid-1995, he was given unescorted leave to spend two days a week on a City and Guilds furniture restoration course, where he met Ms Best the following year.

He was let out by a mental health tribunal 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 by then.

The mother-of-four and grandmother only found out he had killed before when she came across letters at his home and confronted him.

Ms Jones said in her statement to the inquest: “We feel it’s simply not good enough to have relied repeatedly on [Johnson's] self-reporting.”

She has "no doubt" that had her sister been told about Johnson’s history she would have ended the friendship immediately.

Although guidelines stated there should be unannounced visits from the authorities, Ms Jones claims regular unannounced visits did not take place.

“I feel that Angela had no chance and no choice,” she said, adding that Johnson “pulled the wool over everyone’s eyes”.

“People talk about getting over grief but you don’t get over it," she added in her statement.

“I feel that [Johnson] had more rights than Angela or her family who have lost her.”

Ms Jones recalled when Johnson’s flat was flooded and he stayed at Ms Best’s house.

“That was a huge missed opportunity because if [Johnson] had been under stringent supervision, questions should have been asked if his flat was uninhabitable,” she said.

Ms Jones noted her sister had attended hospital with him and they regularly socialised together.

Recalling her sister’s death, Ms Jones said: “When I found out she had been murdered it was like time stood still.

“I honestly think that she stayed in contact with [Johnson] because she was scared of him and she did it to keep the peace.”

When Jamaican national Johnson was last seen by a social worker and psychiatrist on December 8, 2016 - one week before the murder - he was not found to be depressed and denied being in a relationship.

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

But three senior judges later ruled that the sentence was “unduly lenient” and increased the tariff to 30 years.

The inquest, attended virtually by counsel and family members, continues.