Detectives said the 15-year-old was sexually mutilated and her throat cut during a frenzied attack only 100 yards from her home at Ansley Common near Nuneaton, Warwickshire. Her parents agreed to the "disgusting" details being released to help the hunt for the killer.
Detective Superintendent Tony Bayliss said: "I believe that it is right and proper to reveal the extent of Naomi's injuries, so that those who may have mixed loyalties about whether to come forward with information do so."
The killing is the seventh murder of a child or teenager in as many weeks. Each has sent a wave of fear and revulsion through the country, particularly among parents.
Yesterday it was disclosed that Naomi's parents themselves saw the extent of their daughter's injuries at the scene of the crime on Thursday. The freckled-faced schoolgirl had left home just before 10pm to post a letter for her mother, but never returned and was discovered by her taxi-driver father, Brian, and best schoolfriend, Emma Jones.
Mr Bayliss said Naomi's father visited Emma's house hoping to find his daughter there. The pair then went out together searching. He said: "Emma is deeply distressed, as you can imagine. She is now with officers from our specialist child protection unit."
He said Mr Smith and friends travelled around the streets in his car and went to the car park of the recreation ground. They shone the car headlights onto the children's play area and saw Naomi's body, lying under a climbing frame.
Her death follows a summer of violent child killings. In July, Paul Barker, 12, and his best friend, Robert Gee, 13, were stabbed to death while fishing by a pond near their homes on the Wirral, Merseyside. Steven Heaney, 36, has been charged with their murders.
The following day, seven-year-old Sophie Hook was snatched from the tent where she was camping in the back garden of her uncle's home in Llandudno, North Wales. Her battered, naked body was found on a beach half a mile away. Howard Hughes, 30, has been charged with her murder.
In August, Louise Sellars, 15, was found strangled in a copse on farmland near Wigan, Greater Manchester, and the naked body of 13-year-old Darren Fawns was discovered by two Belgian tourists on a golf course near Lough Neagh in Northern Ireland. He had been missing for six days and had been beaten around the head. No one has been charged with either killing.
Last weekend the body of 18-year-old Rachael Lean was found near her home in Buxton, Norfolk. She had been repeatedly stabbed. Maria Hnatiuk, 28, is now in custody charged with her murder.
Although attacks like the one on Naomi are comparatively rare, fewer and fewer young people are allowed out alone as a result of them, according to child safety experts.
Jane Fitzpatrick of the Kidscape organisation said parents now found it harder to strike a balance between vigilance and allowing their children to develop: "There is more traffic, there are more people around and we no longer live in tight communities. When a murder like this happens it makes people even more afraid."Reuse content