Ian Huntley is "unlikely to dispute" that Soham schoolgirls Jessica Chapman and Holly Wells died in his home, a jury has heard.
The girls disappeared last year
Richard Latham QC, prosecuting, told the Old Bailey in London that lawyers representing Mr Huntley indicated they were unlikely to deny the 10-year-olds died soon after entering his home.
The 29-year-old former school caretaker has denied killing the pair, who disappeared from near their homes in the Cambridgeshire town on 4 August last year.
Mr Latham told the court the focus of the trial would be whether or not "it could be construed that the deaths while he was there with them in his house amounted to murder".
He said: "It is unlikely to be disputed by Huntley that the two
girls went into his home... that he was the only other person
there, and that they died within a short time of going inside."
Mr Huntley then drove their bodies to the spot where they were found nearly a fortnight later, close to the RAF base at Lakenheath in Suffolk, the court heard.
Speaking a few feet away from the parents of the two girls, the barrister said: "For some reason known only to him he chose to murder them both.
"We allege that he went on to remove the bodies from Soham."
Mr Latham said police had arrested Mr Huntley and his former girlfriend Maxine Carr after making a "very significant find".
Mr Latham said there was no suggestion Ms Carr had been directly involved in the murders, but said she had helped Mr Huntley to mislead police.
Ms Carr, 26, has denied two charges of assisting an offender and one of conspiring to pervert the course of justice.
Mr Latham told the court Ms Carr had been visiting her mother in Grimsby the day the girls disappeared.
She had travelled there the previous day, a Saturday, but returned on Tuesday 6 August - earlier than planned because of events in Soham.
Mr Huntley denies killing the girls
The prosecution alleges she lied to the police about her and Ian Huntley's whereabouts that weekend and only admitted to police she had been in Grimsby after her arrest.
"It was a calculated and cold-blooded course of conduct... involving repeated lies throughout the period of the disappearance of the girls and her arrest," Mr Latham said.
The court heard details of an alleged phone call between Ms Carr and Mr Huntley on the Sunday evening, in which he said two girls had asked about her.
Mr Latham said mobile phone evidence would prove crucial during the trial in showing the locations of the girls and the defendants.
Retracing the girls' final hours, Mr Latham said Holly and Jessica had been photographed at Holly's house, wearing Manchester United shirts in front of a clock showing 1704 BST.
A little over an hour later, Kevin and Nicola Wells heard the girls in Holly's bedroom through the thin floorboards - the last time they heard them.
The schoolfriends were spotted walking in Soham, described by one witness as looking like "two little Beckhams".
CCTV footage at a sports centre shows the girls walking across the car park, believed to be at 1827 BST.
Fifteen minutes earlier, Mr Huntley had also been spotted near the sports centre, the prosecution claimed.
Tributes were left outside the Old Bailey
The last time a signal was detected on Jessica's mobile was at 1846 BST, Mr Latham said.
He said Mr Huntley's whereabouts were unknown for four hours from 1815 BST - during which time it was alleged he dumped the bodies and made the 40-minute drive back to Soham.
During the night, Mr Huntley helped police searching for the girls by opening up doors around the school.
The girls' bodies were found by three members of the public on 17 August.
On Monday, the jury will visit Soham and on Tuesday the area where the bodies were found.
Richard Latham QC is prosecuting
Mr Latham said Holly and Jessica had been reliable and sensible school pupils.
Maxine Carr became their classroom assistant and was especially liked by Holly, but the girls' teacher thought Ms Carr had been unable to create an appropriate distance.
The barrister said Mr Huntley had owned a red Ford Fiesta in August 2002 - which he said would form a key part of the prosecution case.
Mr Huntley denies two counts of murder but has admitted a single charge of conspiring to pervert the course of justice.
The pair have been held in custody since their arrests on 17 August last year.
The case was adjourned until Thursday morning.