Families of the four victims of serial killer Stephen Port have welcomed a coroner’s report that identifies several areas of concern over the bungled investigations into their deaths.

Sarah Munro QC published her prevention of future deaths report on Tuesday following inquests into the deaths of Anthony Walgate, Gabriel Kovari, Daniel Whitworth and Jack Taylor.

The men all died at the hands of Port, who drugged them with overdoses of GHB and dumped their bodies near his flat in Barking, east London, between June 2014 and September 2015.

Solicitor Neil Hudgell said: “The families remain grateful to the coroner for her detailed consideration of the many issues raised throughout the inquests.

“It is clear to see from the length of the prevention of future deaths report that there remain very many areas still to be addressed, not just by the Metropolitan Police, but by police forces nationally.”

Basic errors by a string of detectives left Port free to carry out a series of murders as well as drug and sexually assault more than a dozen other men.

In December, inquest jurors found that “fundamental failures” by the police were likely to have contributed to three of the men’s deaths.

Ms Munro said she had been “extremely concerned and disappointed” to hear evidence of the blunders.

Setting out overarching issues in the case, she said: “Perhaps the most striking of these is the large number of very serious and very basic investigative failings.

“I have been extremely concerned and disappointed by the evidence that I have heard about these series of errors.”

The coroner acknowledged that the Metropolitan Police had made efforts to identify the causes of the mistakes and make changes, but said addressing a lack of professional curiosity was a key lesson.

Seventeen officers were investigated by the watchdog the Independent Office for Police Conduct (IOPC) over the deaths, and nine were found to have performance failings.

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

Ms Munro highlighted that the inquests had identified officers’ mistakes that were not uncovered by the IOPC investigation.

All but one of the 17 officers under investigation gave no comment interviews to the IOPC, as is their legal right, but several were made to give detailed oral evidence in person to the inquests.

The report also expressed concern over how deaths are classified as “unexplained” rather than suspicious.

Mr Kovari’s death was classed as “unexplained but not suspicious” within five hours of his body being discovered, despite an inspector later admitting they had no idea how he had died, while Mr Whitworth’s death was also classed as non-suspicious on the day he was found, even though investigators had not properly checked that a fake suicide note found with his body was genuine.

The letter had been planted by Port, falsely claiming that Daniel had accidentally killed Gabriel, when in fact the two did not know each other and were not together on the night Mr Kovari died.

This term is still used in Met guidance, and Ms Munro said: “The term ‘unexplained’ as used in the current policy may once again distract officers from the correct and necessary approach, which is for the death to be treated as suspicious unless and until the police investigation has established that it is not.”

Families of the four men believed that homophobia played a part in the failings, and while the coroner did not make her own finding on the issue she said she agreed with a report by the IOPC that suggested “the possibility of assumptions being made about the lifestyle of young gay men and the potential vulnerability of men cannot be ignored, and may reveal that intersectionality was present in policing in 2014/2015, and may still be”.

She also found that police leadership linked to the cases had been inadequate at inspector and sergeant level, including one inspector writing closing reports for Mr Kovari and Mr Whitworth’s deaths that “contained serious material inaccuracies”.

The report said: “More effective leadership might well have meant that other basic errors or oversights would have been corrected, such as the failure to obtain the critical intelligence on Stephen Port that was there to be found, and the delay in getting Port’s laptop examined.

“It is a matter of concern that despite the regularly refreshed training that is now in place for detective sergeants and detective inspectors, and the additional leadership training in which the Metropolitan Police has invested, a lack of ownership and responsibility for the investigations of unexplained deaths may persist in officers who are supposed to be leading investigations into unexplained deaths.”

Other issues highlighted in the report included how news of the deaths were broken to the men’s loved ones.

Ms Munro said: “I was shocked and disappointed by the evidence that I heard, that in three of the four deaths there were errors made by those delivering the death message, and that in the fourth case (Gabriel’s) his family was not even informed by the police of his death, and thereafter the designated family liaison officer never made contact with the family.

“It is obvious that the news of the death of a family member/partner is devastating. It is therefore a basic expectation of the police that they should be able to do this difficult task accurately and sensitively.”

The report acknowledged efforts made by the Met to improve use of internal crime recording systems, but said the coroner remained concerned that officers might not properly log lines of investigation, actions and outcomes.

She said that guidelines on when specialist murder squad detectives should take over investigations from local officers should be made clearer, and said that after another coroner expressed concern about gaps in the investigations into Mr Kovari and Mr Whitworth’s deaths in 2015, this should have led the police to “reconsider the adequacy of their investigation”.

Finally, Ms Munro expressed concern about the Sleepyboy website, that was used by Anthony Walgate in his work as an escort to arrange to meet Port.

She said: “Although there is a verification process for escorts, Sleepyboy does not require any verification from users of the site, which is free to browse and does not require any log-in.

“I am concerned that this means that escorts advertising on the Sleepyboy website are left in a particularly vulnerable position.”