Here is a documentary about an extraordinary episode of outrageous corruption among New York police in the 1980s; a sort of real life counterpart to A Most Violent Year, but without any of the machinations of drama, and a hundred times more appalling.

The backdrop is the chaos-riven New York of recent myth: the bankrupt city swamped by a tide of crack cocaine and violence, with big-money gangsters ruling the streets and honest folk too terrified to step outside their doors. The central protagonist is Michael Dowd, a patrolman in the NYPD’s 75th precinct in the East New York area of Brooklyn (hence the title); having served over 11 years in jail for his eight-year splurge shaking down drug dealers and and stealing from robbery scenes, Dowd tells the camera in impressive – if self-serving – detail how he ended up as one of New York’s most corrupt cops.

From – as he claims – tearing up a traffic ticket in exchange for “a lobster lunch” in the mid-80s to sending police cars to protect illegal cash runs, to planning a hit on a woman whose husband had allegedly skipped with gang money, Dowd’s trip to the dark side was a long and incrementally shameful one. It’s clear that Dowd took full advantage of the police code of silence on wrongdoing in their own ranks, and has much to say on the subject of “rats” – without a doubt aimed at Ken Eurell, his former beat partner who became a prosecution witness in return for a reduced sentence.

The activities themselves, which primarily involved taking backhanders in exchange for protecting large-scale cocaine dealing, and allowing cops to be seen as hirelings of serious criminals, are jaw-dropping enough; Dowd’s unembarrassability is even more spectacular, offering up one or two strategic hairshirt moments – but he appears essentially unrepentant. And the fact that this type of lawbreaking has fundamentally not gone away is testament to the difficulties facing investigators as well as the basic possibilities on offer to those minded for larceny. A sobering, and indeed worrying, film.