The brutal killer of two children has died while serving his double life sentence in prison.

The sister of one of the victims expressed mixed emotions after learning Tariq Rehman collapsed on Monday morning while in the gym.

Rehman, who was 46, was convicted of murdering seven-year-old Jonathan Copley and his babysitter, Rachel Rooney, 15, Mr Rehman's common-law step-daughter.

He shared a house in Adwalton Grove, Queensbury, with Rachel's mother Christina.

Rachel's sister, Sharon, 28, said his death had left her confused and sad.

The mother of three, from East Bowling, Bradford, said: "It is a big shock to me.

"There are mixed reactions in the family.

"He brought me up from the age of three, and was the only man I trusted. For him to be convicted of something like this was confusing.

"This has now just added to that confusion."

Officers at Wakefield Prison made attempts to resuscitate Rehman, at 9.50am on Monday, but he was pronounced dead at hospital an hour later. The Prisons and Probation Ombudsman is to investigate the death - standard practice for all deaths in custody.

Rehman's body has now been returned to Bradford where a funeral took place yesterday evening.

He had denied killing the children in Jonathan's home in Southfield Lane, Little Horton, Bradford, on February 18, 1995.

As he was led to the cells following his conviction in March, 1997, Rachel's natural father, David Rooney, shouted: "I hope you rot in hell."

Both children had their throats cut in one of the most horrific murders to happen in Bradford in recent times.

Rachel, who prosecutor Paul Worsley said had also been sexually assaulted, had been stabbed 48 times and the boy 15 times with a pair of scissors.

The scene had been discovered by Richard's mother, Denise Copley, her 15-year-old daughter Elizabeth and a friend when they returned home.

Before she died at the age of 40, in August, 2000, Mrs Copley became a trustee and active member of the national campaign group, Mothers Against Murder And Aggression (Mamaa), alongside Rachel's grandfather, John Clarke.

Mr Clarke died just two months after Mrs Copley, aged 62.

The families of both campaigners said the continued grief and stress of the tragedy affected their health.

Mamaa was set up in 1993 following the murder of Liverpool toddler James Bulger and supports families nationwide who have suffered the trauma of having a child murdered.

In the years leading up to her death, Mrs Copley, who lived in Wibsey, campaigned for better local services, including a respite retreat for victims' families.