The police watchdog is to reinvestigate the Metropolitan Police over their initial handling of the murders of four young men by serial killer Stephen Port.

The Independent Office for Police Conduct (IOPC) said there is evidence that its original investigation into the conduct of officers was “materially flawed”, with “new information” coming out at the inquests into the deaths of Anthony Walgate, Gabriel Kovari, Daniel Whitworth and Jack Taylor, held last year.

The inquests concluded that police failings “probably” contributed to the deaths of the three last victims, all of whom were unlawfully killed.

None of the 17 officers involved in the original IOPC investigation – carried out before the inquests – faced disciplinary action, although 16 of them gave “no comment” interviews.

The victims’ families said the IOPC’s announcement on Thursday was “the only logical decision open to the IOPC following the weight of evidence heard at the inquests”, and accused the police of having “blood on their hands” after Port’s killing spree was only stopped following the fourth murder.

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Daniel Whitworth, Jack Taylor, Anthony Walgate and Gabriel Kovari were murdered during a 16-month period by Stephen Port (Metropolitan Police/PA)

The Metropolitan Police said they would offer “every support” to the fresh investigation.

IOPC regional director Graham Beesley said: “Since the inquests concluded, an IOPC team has been closely examining the original investigation material and comparing it with the information and verbal accounts provided to the new inquests.

“A matter can only be reinvestigated by the IOPC if we are satisfied that the original investigation was materially flawed in a manner which had an impact on the subsequent decisions made on discipline, performance and/or referral to the Crown Prosecution Service, and/or there is ‘significant new information’ that requires further investigation.

“In this case, the reinvestigation process has identified evidence which meets both the significant new information and material flaw categories, and we believe a proportionate – but thorough – new investigation is in the public interest.”

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The families of Stephen Port’s victims at Barking Town Hall, after an inquest jury found that police failures over Anthony Walgate’s murder ‘probably’ contributed to the other men’s deaths (Stefan Rousseau/PA)

He said the decision to reinvestigate “does not necessarily mean that the entirety of the original investigation will be examined again”.

The inquest jury found that officers in Barking missed repeated opportunities to catch Port after he plied his first victim, Mr Walgate, with a fatal dose of the date-rape drug GHB and dumped his body.

Port struck three more times before he was finally caught, killing each victim in near-identical circumstances, with police failing to link him to the deaths despite detective work carried out by the victims’ family and friends that would lead them to the culprit.

Officers had denied accusations of prejudice and homophobia, instead blaming mistakes on being understaffed and lacking resources, with some acting up in senior positions.

Solicitor Neil Hudgell, speaking on behalf of the victims’ families, said the original IOPC report “was hindered by a wall of silence”, given that nearly all officers questioned gave “no-comment” interviews.

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The locations where bodies were dumped by Stephen Port during his 16-month killing spree (Metropolitan Police/PA)

He said: “Our hope now is that the IOPC will have a lot more to go on.

“There remains a big question mark over whether police prejudice played a part in the investigations.”

He added: “The inadequate investigations by the Metropolitan Police into the four deaths is one of the most widespread institutional failures in modern history, exacerbated by a woeful lack of remorse, regret or sympathy displayed at the inquests by some of the officers involved.

“Port was jailed for life, but the police have blood on their hands too. It is time for them to be held accountable.”

Port, now 47, a former bus depot chef, will die in prison after being handed a whole life sentence at the Old Bailey for the murders in 2014 and 2015, as well as a string of sex assaults.

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The location outside Stephen Port’s former flat in Cooke Street, Barking, where the body of his first victim, fashion student Anthony Walgate, was found (Emily Pennink/PA)

Nine of the 17 officers investigated by the IOPC in 2018 were found to have performance failings.

But none of the nine were disciplined or lost their jobs, and some have since been promoted.

Acting Deputy Commissioner Helen Ball said: “The deaths of these four young men is a tragedy and we are deeply sorry there were failings in our police response. Again, I give my own and the Met’s heartfelt apologies.

“The whole of the Met is committed to improving our investigations, our relationships and the trust people have in us to keep them safe.

“Her Majesty’s Inspectorate of Constabulary and Fire and Rescue Services are with us now, carrying out an inspection into how we respond to and investigate death. We look forward to their findings and any recommendations they may have.

“If the IOPC reinvestigation makes further recommendations for improvements we will, of course, consider those very seriously, in addition to any misconduct matters that may arise.”