A police officer who handled the early phase of the investigation in the death of the first victim of a serial killer Stephen Port has asked for legal representation in an upcoming inquest.
Port, 45, drugged and raped four men and left their bodies near his home in Barking, east London, in 2014 and 2015.
An inquest into his victims' deaths is scheduled for January and expected to focus on possible failings by police.
Victims' families have questioned why he was not stopped sooner.
Port is now serving a whole life term for the murders of fashion student Anthony Walgate, 23, Gabriel Kovari, 22, chef Daniel Whitworth, 21, and forklift truck driver Jack Taylor, 25.
A pre-inquest review on Friday heard Det Supt Mike Hamer, former deputy borough commander for Barking and Dagenham, is seeking to be named as an interested party at the inquest, meaning he will have legal representation.
He was involved in the first two weeks of the investigation into the death of Mr Walgate.
Det Supt Hamer's legal counsel, Nicola Howard QC, told the Old Bailey his involvement had been of "relatively short duration, but during possibly the most critical point of time" following the discovery of Mr Walgate's body.
Three of the victims' bodies were found in the graveyard of St Margaret's Church, Barking, but Port dumped the body of Mr Walgate on the street outside his flat before calling emergency services.
He claimed the victim had suffered a seizure or was drunk, but was later convicted of perverting the course of justice after giving differing accounts to police about what had happened.
Evidence linking Port to the killing was missed at the time, and he went on to kill Mr Kovari and Mr Whitworth while on bail for perverting the course of justice.
Ms Howard said Det Supt Hamer had made decisions on how the case should be progressed, including the allocation of resources.
"It's clear that his involvement was critical and was crucial for a number of reasons - it must be considered that it shaped the ambit of the investigation in those critical weeks," she said.
She added his involvement in the assessment of whether Mr Walgate's death was suspicious or non-suspicious, and if that assessment was appropriate in light of what was known at the time, "is one of the issues set out in the scope of the inquest".
Ms Howard said his role might be considered in relation to "significant generic issues" including "whether the police investigations were affected by prejudice or lack of understanding, whether any investigation failures or shortcomings that may be established are attributable to senior officers".
She added if he was not represented, others might try to "push responsibility and blame to his door, distorting the true picture in terms of the evidence".
Counsel to the inquest Andrew O'Connor argued it was unnecessary for the officer to be made an interested party.
"We submit that, even if there is criticism of Det Supt Hamer's conduct, it doesn't amount to a causative, or even a potentially causative link between that conduct and the later deaths," he said.
At a previous hearing, the court heard lawyers for the victims' families were calling for prospective jurors to be quizzed on their "beliefs or moral attitudes" towards gay people.
Paul Clark, for the victims' families, said such a question was relevant in how jurors would treat one of the "core issues" - whether there were "unjustified differences" in the way gay people were treated by police.
At Friday's hearing, Mr O'Connor argued such a question should not be introduced, as the fact a juror holds a particular belief cannot be grounds for dismissing them, or interfere with the principle that juries should be randomly selected.
Coroner Sarah Munroe QC said she would give a written ruling on the issues raised at the hearing in the next few weeks.