Stephen Port has been found guilty of murdering four young men and raping four others. After the first death, police arrested him and took his DNA. So how did he go on to kill three more men?

At the end of summer 2014, three weeks apart, the bodies of two young men were found in the same east London churchyard by the same woman walking her dog.

Both men were of a similar build. Both in their 20s. Both propped up in the same position in the graveyard.

Both men were gay. Both died from drug overdoses. Neither came from Barking, the area in which they had been found.

Police deemed the deaths of the men found in the churchyard, Gabriel Kovari and Daniel Whitworth, to be non-suspicious.

An apparent suicide note found with Whitworth’s body appeared to explain what had happened. Kovari had died after taking drugs during sex, the note said, and a guilt-stricken Whitworth had taken drugs in order to end his life, it suggested.

But a year later – in September 2015 – another body was found, propped up on the other side of the churchyard wall. Again it was a young gay man – Jack Taylor – who had died of a drug overdose.

How could this be coincidence? Three men found dead within a few feet of each other.

But the key to the case was another man, Anthony Walgate, who had died nearby before any of the others.

He had been found only 500m from the church, outside the flat of a man named Stephen Port.

The truth was that Port had killed all four men and then fooled the authorities with a cover-up that, while elaborate, should have been easily uncovered.