The haunting thing is that it happened in such plain sight. A couple driving home through London late at night saw a man putting police handcuffs on a young woman on the street. Something unspeakable was unfolding right before their eyes but they didn’t know – how could they have known? – what they were seeing. They simply thought it was an undercover arrest. Heartbreakingly, at first Sarah Everard would have thought so too. When Wayne Couzens drove up beside her as she walked home from a friend’s house, brandishing his police warrant card and claiming she was under arrest for supposedly breaching lockdown regulations, she didn’t resist. She did what the policeman said, just as millions of women would have. Only once she was in his car, powerless to escape, would she have realised something was terribly wrong. There could be no more grotesque betrayal of trust, no more rank abuse of power. The judge who this week sentenced Couzens to a rare whole-life sentence for Sarah’s kidnap, rape and murder rightly cited police officers’ unique responsibility to use their “powers of coercion and control” for the public good. But slamming the cell door won’t fix shattered faith in the force, and nor will Met commissioner, Cressida Dick, promising merely to “learn lessons” when her force seemingly failed to spot a killer in its midst. For Couzens was, in a sense, hiding in plain sight for years. He made female colleagues in his first job so uncomfortable that they nicknamed him “the rapist”. He would reportedly stop female motorists, noting their details and then return to watch their homes, and park his patrol car outside schools, checking out teenage girls and their mothers. Most shockingly, he was reported twice for indecent exposure in London in the weeks before Sarah’s murder, yet still somehow managed to continue working. Two fellow officers are under investigation by the Independent Office for Police Conduct over their handling of those reports. But women will also want to know what lies behind former Met Ch Supt Parm Sandhu’s claim, post-sentencing, that female officers are frightened to report suspicious colleagues, in case the men close ranks and leave them in the lurch when they need backup in a dangerous situation. If policing in this country is by consent, that consent feels suddenly very fragile. Women are now anxiously asking questions that for some would once have been unthinkable. If you’re driving home alone, and an unmarked police car signals for you to stop, should you? How should you respond to a lone woman being arrested on the street? What if a detective knocks on your door, supposedly with a warrant, late at night? This may all sound naive to some black and brown Britons who learned their suspicion of the police the hard way, and for whom these questions will be nothing new. Some may wonder, too, why cases like that of Dalian Atkinson – a black ex-footballer who died after being repeatedly Tasered and then kicked in the head by police officer Benjamin Monk, who was jailed this summer for his manslaughter – didn’t trigger this kind of national outrage. Of course, it’s a form of privilege to have grown up trusting the police, or to have a faith still capable of being shaken. But “privileged” isn’t quite the word for women who have met with callousness or disbelief when reporting their own experiences of sexual or domestic violence, yet are nonetheless still shocked by the idea of an officer actually committing cold-blooded murder. Now rage at Sarah’s betrayal is reaching the places where the police could once count on unthinking support, causing some perhaps to understand for the first time what others have felt for much longer, driving a clamour for change. Dick, who earlier this year said that with a workforce of 44,000, you will occasionally get a ‘bad ‘un’, apologised for an officer who she said had brought shame on his force and acknowledged that for some “a precious bond of trust has been damaged”. But she has yet to show she grasps the scale of response needed to restore it. Harriet Harman, the former Labour justice secretary, is right to say Dick should now offer her resignation – but more importantly, that sweeping changes must follow. And so must an independent inquiry. Murder is rare, and murders like this one vanishingly more so. But Couzens wasn’t the only rotten apple in the barrel. Since 2009, at least 15 serving or former police officers have been convicted of murder, in most cases of their wives or girlfriends, according to the Femicide Census database. Over the last two years, more than 125 women have come forward alleging that their police officer partner abused either them or their children, and that may be the tip of the iceberg. Imagine mustering the courage to call 999, knowing it might be one of his mates who is sent to respond. Former Scotland Yard deputy assistant commissioner David Gilbertson has warned of an “epidemic” of hidden violence, including cases where officers in domestic violence units “actively searched out vulnerable women for sexual gratification, and in order to gain access to their children for sexual purposes”. Among a grim catalogue unearthed by the Observer was a Met officer dismissed for taking advantage of a rape victim whose case he was investigating. And yes, that’s a handful of rogues among countless decent (and doubtless appalled) officers. But every one is a reminder that predatory men will seek out jobs offering control over women, or cover for exploiting them. Kate Wilson, an environmental activist duped into a sexual relationship with a man she’d never have slept with had she realised he was an undercover police officer, won a landmark human rights case against the Met on the very day Couzens was sentenced. Heaven knows how many women have stories of more minor, but still disturbing, creepiness. What happened to Sarah is its own unique tragedy. But in its wider impact the closest comparison is to men exploiting positions of trust – as headteachers, priests, or politicians – to abuse children, or even perhaps with Harold Shipman, the GP thought to have murdered at least 218 elderly patients before being caught. Worried that people would be too terrified to go to the doctor, the Department of Health ordered an independent inquiry to identify the loopholes that allowed Shipman to kill with impunity, and to close them. Restoring female trust in the police now requires the same. The “boundless love” with which Sarah’s family told the court they would remember her must be matched in the criminal justice system by a boundless resolve to change. Gaby Hinsliff is a Guardian columnist