The man who killed teenage model Sally Anne Bowman may have used her mobile phone to take pictures of the crime scene, police have said.
Sally Anne Bowman was murdered near her home in south London
Ms Bowman's final hours were reconstructed on BBC One's Crimewatch on Tuesday, prompting 130 calls.
Police said they believed a man seen walking towards the scene a short time after the attack was the killer.
Ms Bowman, 18, was stabbed to death outside her home in South Croydon, south London, on 25 September.
Det Chief Insp Stuart Cundy told the programme the level of violence used was "off the scale".
"I can't get across in words what I saw with my own eyes," he said.
Ms Bowman, who dreamed of being on the cover of Vogue, was bitten and stabbed to death before being sexually assaulted.
Her belongings including a Prada handbag, purse, mobile phone and bolero top may have been kept by her killer as trophies, he added.
The reconstruction showed Ms Bowman getting out of her ex-boyfriend's car, being attacked and the suspect throwing away some of her things after the murder.
It prompted an "amazing" response within minutes, presenter Fiona Bruce said, with 30 names being put forward by callers.
Later, the film showed a witness spotting a Ford Mondeo parked in Blenheim Park Road, at the junction with Blenheim Crescent, with the doors open while a man leaned against a fence.
Police said he may have seen or heard something that might help catch the killer.
Detectives think Ms Bowman's attacker may be a serial rapist after tests linked her murder to an attack in Purley in 2001.
It is thought he was lying in wait for her as she returned home after a night out in Croydon town centre.
The murder suspect is described as white, in his 20s or 30s, with short brown hair and is between 5ft 9in and 6ft tall.