Peter Foster, 36, was jailed for at least 17 years at Lewes Crown Court last month after admitting murdering Heather Cooper, whose body was discovered in a shallow woodland grave. The 33-year-old was killed at the couple's home in Haslemere, Surrey. Foster's death, at Lewes Prison, comes three days after a man who knifed his stepfather to death was found hanged. Nathan Vaughan-Jones, 34, was found at about 20:30 BST on Friday at the prison and pronounced dead about 30 minutes later. He had been jailed for 11 years in March 2012. Vaughan-Jones admitted the manslaughter of 63-year-old Nigel Ross on the grounds of diminished responsibility after he stabbed him 41 times in the garden of his sister's home in South Chailey, near Lewes. It is understood Foster was subject to suicide-prevention measures at Lewes jail. Heather Cooper was found dead in woodland a few miles from her home in Haslemere last October The Prison Service said he was found hanged in his cell at 03:00 BST. "Prison staff tried to resuscitate him and paramedics were called but he was pronounced dead at 03:25," said a spokesman. "As with all deaths in custody, the independent Prisons and Probation Ombudsman will conduct an investigation. "We will now consider if these cases were completely isolated or if there were any common factors involved." Foster stabbed Ms Cooper, a detective constable with Surrey Police, while she was on maternity leave in October last year following the birth of her second child. He then