The jury in the Ian Huntley double murder trial has been told to "resist pressure" as the case nears completion in the Old Bailey .
The prosecution says Mr Huntley killed the girls
Stephen Coward QC made the plea during his summing up on Wednesday, following the prosecution's closing statement.
He also said that although the former school caretaker denies murdering the 10-year-old friends last year, there was evidence of manslaughter.
Mr Coward said Mr Huntley was not innocent nor unworthy of punishment.
He told the jury: "We conclude on the evidence available, thin as it is, that there is evidence that Mr Huntley is guilty of the manslaughter both of Holly Wells and of Jessica Chapman."
He added: "Let's be blunt. On the evidence you have heard, we are not going to argue on behalf of Huntley in the case of either girl that what he did makes him innocent
and unworthy of punishment."
The prosecution's suggestion that Mr Huntley had a sexual motive in inviting the pair in to his house was "a classic case of the prosecution looking through twisted
"They treated it as sinister from the start and we submit there is evidence, and the only evidence there is, which suggests it was entirely innocent from the start," Mr Coward said.
Mr Coward accused the other defendant Maxine Carr of "character assassination" as she tried to distance herself from her former boyfriend.
Ms Carr denies conspiring to pervert the course of justice and two counts of assisting an offender.
Holly Wells and Jessica Chapman died in August 2002
Mr Coward added that Ms Carr's legal team had not challenged Mr Huntley's testimony, where he said he had changed the carpet in his car boot months before the girls died - not
while Ms Carr was in Grimsby, as she later told court.
Earlier, prosecuting counsel Richard Latham QC described Mr Huntley as a ruthless liar who killed the two girls.
But Mr Coward asked jurors to stick together, disregarding outside influences when making their decision on a case that had gone "deep into the psyche of everyone in Britain".
Mr Coward said in many vital areas, such as how and when the girls died, there were many "blank spaces".
His closing speech follows the prosecution's summing up earlier on Wednesday.
During his evidence Mr Huntley claimed Holly died accidentally after falling into his bath last August when he was helping her with a nosebleed.
However, he admitted he had killed Jessica by putting his hand over her mouth to stop her screaming and that he had told lies to police to cover his tracks.
Mr Huntley also admitted dumping the girls' bodies in a ditch and trying to burn them.
Mr Latham, said "ruthless" Mr Huntley's account of both deaths were "desperate lies".
He said "the whole business in the house was motivated by something sexual" that had gone wrong.
He said Mr Huntley had had "nerves of steel" to have carried a series of media interviews knowing the girls were dead and to have actively sought out Holly's father Kevin for a conversation.
The defendant had also conducted "a series of ruthless acts" by dumping the bodies of the girls in a remote ditch and cutting off their clothes to remove potential evidence that would link him, Mr Latham said.
The case was adjourned until Thursday.