It was while working for the Civil Nuclear Constabulary, which he joined in 2011, that Couzens was given the nickname "the rapist" by fellow officers because of the way he behaved towards female colleagues.
He reportedly "gave women the creeps" but, in the male-dominated world of policing, none of the women made a formal complaint against him.
Since his arrest, several women have come forward to make historic allegations of harassment against him, and the Home Secretary is now under pressure to order a review of whistleblowing protocols in all police forces.
He warned that police officers were failing to raise concerns about colleagues and blamed a "culture of colleague protection" within the service, adding: "In too many respects, there is evidence of police officers who become aware of damaging or worrying characteristics in police officers of not reporting them, not putting up a warning flag, and that needs to change."
Couzens is now known to have repeatedly
exposed himself while driving – an offence which would almost certainly have ended his police career if it had been detected at the time.
In June 2015, a male motorist made a complaint to police that he had seen a man driving around Dover naked from the waist down. This time it was Kent Police that had a golden opportunity to root out the future murderer but, once again, he slipped through the net.
Couzens was identified as the suspect, but for reasons that remain unclear he was not arrested and his then employer, the Civil Nuclear Constabulary, was not informed. Kent Police marked the investigation as "no further action".
The incident only came to light when it was disclosed earlier this year by the IOPC, which is investigating alleged failures in the case after Kent Police referred itself to the watchdog.
Couzens gave police one more chance to catch him when he returned to his habit of flashing just days before he murdered Miss Everard.
On Feb 28, a member of staff at a McDonald's drive-thru in Swanley, Kent, called the police to report a man in a car who was naked from the waist down. Female members of staff are understood to have seen him do the same thing the previous day. CCTV clearly showed Couzens' car, but he was not arrested.
The Met said on Thursday that the complaint was correctly recorded and allocated to an officer for investigation but inquiries had not been concluded by March 3, the day Miss Everard was kidnapped.
The force also confirmed that it had identified the vehicle shown on the McDonald's CCTV but that Couzens had not been identified as the registered owner before he raped Miss Everard and disposed of her body in the same car. Two officers from the Metropolitan Police, which covers Swanley, are being investigated by the IOPC for possible breaches of professional standards that may amount to misconduct.
The police blunders that left Wayne Couzens free to murder Sarah Everard