Serial killer Stephen Port was obsessed with messaging men on hook-up sites and watching drug rape pornography, an inquest has heard.

The 46-year-old, who will spend the rest of his life behind bars for murdering four men and sexually assaulting several others, began taking the drug GHB in late 2013.

He went on to kill Anthony Walgate, 23, Gabriel Kovari, 22, Daniel Whitworth, 21, and Jack Taylor, 25, with overdoses of the drug between June 2014 and September 2015, dumping their bodies near his flat in Barking, east London.

Port was jailed at the Old Bailey in 2016 and the long-awaited inquests are now taking place into his victims’ deaths, examining whether the series of investigations into their murders were adequate and whether lives could have been saved.

Giving evidence at Barking Town Hall on Wednesday, Detective Inspector Mark Richards gave details of his work on Operation Lilford, the investigation launched after the four deaths were linked.

He said analysis of Port’s laptop, originally seized when officers were first investigating the death of fashion student Mr Walgate, showed hundreds of thousands of lines of messaging about sex, pornography and drug taking.

“It was absolutely incessant”, he told the jury. “It was all day, every day.”

“There were hundreds of thousands of lines of messages because he was obsessed.”

Port would watch “a considerable and extensive amount” of drug rape pornography, viewing it for hours at a time on his laptop.

The officer said: “He had a real obsession with drug rape pornography.”

Patterns would emerge where Port would pause messaging or watching the footage for around half-an-hour to go and meet men at Barking station and bring them back to his flat.

He would then continue viewing the material once the men were in his home.

The inquest heard that as well as the murders, Port was found guilty of the drugging and sexual assault of seven living victims at his Old Bailey trial.

In addition there were around six other living victims identified by police who did not wish to take part in the prosecution.

Detectives sifted through details of nearly 60 other deaths to make sure Port had not claimed any more lives, and concluded no accomplice was involved.

Their theory was that 6ft 5in Port had wrapped his victims’ bodies in bed sheets and carried them to the sites where they were found.

The inquests were adjourned until Thursday.