John Sweeney's children speak out about gruesome sketch serial killer father showed them

Until I Kill You is airing on ITV and it explores how serial killer John Sweeney's artwork would eventually lead to his conviction.

Until I Kill You returns to ITV and the series was inspired by the memoir of John Sweeney's only known surviving victim, Delia Balmer. In the series, Delia (played by Anna Maxwell-Martin) comes across a hoard of disturbing drawings of decapitated women and other violent scenarios.

After an almost fatal attack on Delia, the real Sweeney went on the run for six years before he was finally caught and found guilty of two murders. Leading up to his conviction, police found hundreds of disturbing artworks by Sweeney.

On the back of a scratchcard he had written a poem about his first girlfriend and murder victim, Melissa Halstead, whom he had chopped up and disposed of in a canal: "Poor old Melissa, chopped her up in bits, food to feed the fish, Am*dam was the pits."

One painting, entitled One Man Band, contained a drawing of a woman believed to be Melissa. Correction fluid had been painted over a small area.

An ultraviolet light revealed a gravestone with the inscription "Melissa Halstead, born 7 November 1956. Died." Sweeney's son Michael previously spoke out about when his dad showed him "a sketch he drew of my mum in a coffin".

The killer had leant over and handed Michael, a teenager at the time, a gruesome sketch of his mother lying dead in a coffin, with the words Rest in Peace Ann.

At first, Michael, who has a sister called Tracey, thought it was just his dad being bitter after their relationship broke down.

After Sweeney was convicted of two murders, Michael realised the chilling truth behind the disturbing image.

In a previous Mirror report, he had said: "I could see it was my mum straight away. It was so lifelike. It was like a photograph.

"I thought at the time it was strange but just a symbol of their bad relationship. Now I know he has killed I can’t help but wonder, ‘Why didn’t he kill my mum?’”

Michael said he feared his father had killed more victims and he needed to come forward to "put the victims’ families and his own family out of their misery".

He had asked his father whether the woman in his drawing was Ann, to which he just said "yes" and appeared withdrawn.

Just before Ann died in 2002 Sweeney wrote to tell her he still loved her. “He was obsessed with her. I think they were married twice and divorced twice,” Michael explained.

Sweeney is currently serving a life sentence in prison and his son has no interest in seeing him again.

He did come across him once, at a family funeral - an experience he described as "quite haunting".

Ann had made attempts to escape Sweeney, but for some time he continued to chase her.

Until I Kill You continues on ITV at 9pm