David Carrick, a serial rapist and sex offender, spent twenty years in police uniform and, for most of that time, carried a gun.
In private life, he told his victims: "You are my slave" while controlling and abusing them, subjecting them to shocking acts of humiliation.
They will never believe you, because it will be your word against the word of an active member of the police - Kerik would tell them.
Kerik has now admitted to 49 counts relating to 12 victims.
His admissions have once again forced the City of London Police - the police service he worked for - to apologize for failing to recognize the criminal in uniform.
Kerik was finally stopped when a woman decided to report him.
In October 2021, as news of disgraced London police officer Wayne Cozens became public, she contacted police in Hertfordshire, where Carrick lived and committed many of his crimes.
The woman described how she met Kerik through Tinder, a dating app, a year earlier.
During their first meeting, he showed her a police ID, claimed to know her celebrities - including the Prime Minister - and told her she was handling firearms.
He also mentioned his pet snake to her.
He told her he wanted a submissive wife.
After giving her a drink, he took her to a hotel room, where, she said, he raped her.
Kerik was arrested and charged.
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"The investigation turned into an avalanche"
At his first court appearance, he denied all charges - but because he is a defendant in the court case, Carrick's name has been released.
Chief Inspector Ian Moore, of Hertfordshire Police, who led the investigation, describes how this first report served as the trigger.
Seeing him finally in the dock, Carrick's many victims - previously intimidated and silenced - gradually began to come forward.
"The investigation turned into a real avalanche," says Chief Inspector Moore.
The woman who first reported him had no idea that she would encourage so many women to tear the mask of law and order from one monster.
The city police had to apologize after it emerged that they and three other police departments had been tipped off to Kerik nine times.
Deputy Police Commissioner Barbara Gray said the police service "had to notice his pattern of abusive behaviour".
She says the omission "may have prolonged" the suffering of Carrick's victims.
Carrick's earliest known victim described being falsely arrested, raped and threatened with an imitation gun in 2003, near the end of his probation as a police officer.
After that, he raped, sexually assaulted and abused a number of women, calling them his prostitutes.
He would order some of them what to wear, where to sleep and what to eat, sometimes even completely denying them food.
He forbade some to speak to other men or even to their own children.
He urinated on others.
One woman described how Kerik whipped her with a belt, and another described how he regularly locked her in a crate under the stairs.
She remained there "intimidated and humiliated until he decided when she could leave," says Chief Inspector Moore, adding:
"I've seen bigger dog cages."
He says Kerik entered into relationships with women to "satisfy his appetite for humiliating and controlling them."
"He thrived on humiliating victims," claimed Chief Inspector Moore.
The three women were in "controlling and coercive" relationships with Carrick.
And the police believe that there were probably more victims.
Hertfordshire Police Service has opened a separate section on its website, allowing people to make reports directly online without having to go through the police control room or the general online reporting system.
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'Sexual activity'
BBC News also spoke to a woman who met Carrick through an online dating site.
He did not attack her and she is not one of the women in this case.
Although the two did not go out, she did go to his house once.
She describes how he started bombarding her with messages that "really freaked her out".
"He was a real weirdo," she says.
"I thought I should be nice to him because he's a police officer - but I also thought that surely I can trust a police officer."
In the messages, Kerik told her he thought he had fallen in love with her and accused her of pulling his nose.
She is shocked and appalled by the crimes of a man she considered nothing more than a brat and a freak.
During police interviews, Kerik appeared relaxed, claiming that the sexual activity was either on a mutually voluntary basis or that it never happened.
And for months, it looked like his victims would have to go through a harrowing trial period, as Carrick denied all charges.
And then, suddenly, in December 2022, he confessed to most of the crimes.
He was still scheduled to appear in court in February on the remaining counts of the indictment, but he has now pleaded guilty to those as well.
His verdict forces the police to answer some awkward questions.
Kerik started working in the City Police at the age of 26, in 2001, after serving in the army.
He went through the vetting procedure, although in the previous year he was twice accused, although not arrested or charged, of possible criminal acts - among them a burglary of his ex-partner, whom he refused to accept that they were no longer in a relationship.
In 2002, as a rookie police officer, Kerik was investigated in his own police department after he was accused of assaulting and harassing his ex-partner.
No criminal charges were brought against him and he was not referred to the Directorate for Professional Standards of the City Police.
During his career, Officer Kerik was reported several times for assault, harassment and domestic violence, but none of these led to prosecution.
He was on the radar of police in Hertfordshire, Hampshire and Thames Valley.
One charge was made in 2009, when Kerik became a member of armed teams guarding the Houses of Parliament, government offices and diplomatic missions.
In 2017, he passed the procedure of a repeated police check - but two years later he was accused of grabbing a woman by the neck.
Once again, no criminal charges were filed.
And although the City Police was informed, they decided not to initiate disciplinary proceedings.
In the summer of 2021, Carrick was charged with rape and arrested by Hertfordshire Constabulary, but was allowed to continue working - with reduced duties - by the City Police.
While the Metropolitan Police has publicly pledged to protect women after Sarah Everard's murder, it now admits its professional standards department made no effort to check the full record of another officer accused of rape.
"Step Back"
Gray, who recently took over the department, says she still can't believe what happened, noting that Carrick should have gone through a re-vet process and been suspended.
The investigation into the accusation of rape was not initiated because the woman withdrew the report.
And Kerik was about to return to full duty when he was arrested again, this time on another charge of rape.
He was indicted, publicly named and his 17 years of wrongdoing finally came to light.
The city's police have asked the police watchdog to launch a review of their own decision-making process in Carrick, a case Gray describes as "devastating for the victims who had to endure the pain and suffering inflicted on them by an active member of the police service."
"It's devastating to the trust of women and girls across London that we work so hard to build," she says.
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