Video report by ITV News correspondent Richard Pallot
Levi Bellfield has finally admitted killing teenager Milly Dowler - four years after he was convicted of her murder.
The former bouncer made the confession behind bars, where he is serving a whole-life term life for killing Milly and two other women.
Bellfield, who has converted to Islam in prison and now calls himself Yusuf Rahim, said he did abduct, rape and murder the 13-year-old.
He made the admission during an investigation whether he had an accomplice.
A Surrey Police spokesman said: "During this investigation police spoke to Levi Bellfield and he has admitted his responsibility for the abduction, rape and murder of Milly Dowler.
"Despite his conviction, this is the first time Bellfield has made such admissions to police."
Amanda Jane "Milly" Dowler was just 13 when she was snatched near her home in Walton-on-Thames, Surrey, on 21 March 2002.
Earlier that day she had left school at 3pm to go home on the train and got off one stop before her usual stop to meet friends in a cafe.
At 3.47pm she phoned her father and told him she would be home in half an hour - but she never arrived.
Milly was last seen 18 minutes later by a friend of her sister Gemma but it is believed she was abducted, raped and killed shortly afterwards.
Her parents reported her missing at 7pm that evening.
The discovery of Milly's body
Milly's body was not discovered until 18 September 2002 when mushroom pickers found decomposed human remains in Yateley Woods in Hampshire.
Dental records later confirmed it was Milly - but the body was by then so decomposed detectives could not ascertain an exact cause of death.
She was unclothed and none of her possessions - her purse, rucksack or phone she had with her when she disappeared - have ever been recovered.
The discovery of her body led police to launch a murder investigation.
Suspects in Milly's murder
Initially Milly's father Bob Dowler was the original suspect after it emerged Milly found pornographic magazines at their home.
He was subsequently cleared of any wrongdoing and police later apologised for the missed opportunities this may have caused.
Bouncer Levi Bellfield lived just 50 yards from where Milly vanished but did not become a suspect until he was arrested for other crimes in 2004.
It was not until 2008 that police confirmed he was the primary suspect and they were "very interested in questioning him".
On 30 March 2010 Bellfield was charged with Milly's murder and abduction.
He denied the charge but was convicted by a jury on 23 June 2011 and told he would die behind bars.
Bellfield's other crimes
At the time Bellfield was charged with Milly's murder he was already serving life in prison for killing two other women.
Gap-year Marsha McDonnell, 19, died two days after being battered three times on the head with a lump hammer in Hampton, west London on 3 February 2003.
Bellfield then carried out an almost identical attack on French student Amelie Delagrange on 19 August 19 2004, which led to him being dubbed the "bus stop stalker".
He was arrested for the hammer attacks in 2004 but not charged until 2006.
An Old Bailey jury found him guilty of the murders after a trial in October 2007.
He was also convicted of the attempted murder of 18-year-old Kate Sheedy, who was mown down by a car on 18 May 2004.
Phone hacking pay out
In 2011 it emerged the News of the World newspaper had hacked Milly's phone after she was reported missing.
It was reported messages left by family members were intercepted, and some deleted, giving her parents the false hope she was still alive.
Her family were later awarded £2 million in compensation from News International and an extra £1 million from Rupert Murdoch himself which they donated to six charities.
The Dowler family
Today brought the news the Dowlers had been waiting to hear for 12 years.
Despite already Bellfield already having been convicted of Milly's death they said his admission was "devastating" for them.
A statement released on their behalf said: "The Dowler family has been made aware of the recent arrest.
"They have been aware for some considerable time that a new police investigation was taking place into the circumstances of the abduction and murder of Milly.
"The effect of this information has been devastating for a family which has already had to endure so much."