The case against a man accused of murdering care worker Ffion Wyn Roberts is "clearer and stronger" since the trial began, says the prosecution.
Making her closing speech in the trial at Caernarfon, Elwen Evans QC said evidence linked wool packer Iestyn Davies to her death.
The body of the 22-year-old was discovered in a drainage ditch in Porthmadog, Gwynedd, in April 2010.
Mr Davies, 54, from Porthmadog, denies murder and the trial continues.
In her final address to the jury, Miss Evans opened her speech by reminding the jury of the words of Mr Davies's friend who claimed the defendant used swear words as he voiced his hope that the killer would be caught.
Miss Evans said: "Iestyn Davies - the cool, calm, collected, controlled man who never panicked."
She said that if the defendant had nothing to hide he could have helped the police but did not do so because he was the killer.
He had lied when quizzed by police, she alleged.
There had been appeal notices for anyone out between 4am and 8am on the day of Ms Roberts's death to contact police.
She said: "On his own account the defendant is saying 'I went out three separate times between four and eight that morning'.
"So what does this man, who says 'I hope they catch the bastard,' do? Absolutely nothing."
Miss Evans said the defendant had lied to police, including when he claimed that tracksuit bottoms found in a sluice gate were not his.
Nine fibres were found on the clothing that matched those found on leggings and underwear belonging to Miss Roberts, she said.
The jury were also told that DNA evidence linked Mr Davies to a scarf used to strangle and gag Miss Roberts, and also on her torn T-shirt and handbag.
Miss Evans said Mr Davies had been "very anxious" to tell the jury that he saw Miss Roberts the night before she was murdered, almost exactly a year ago.
She said he needed to try and explain the scientific evidence, but CCTV images did not support his story and a barman was sure the defendant had not at Porthmadog's Station pub that night.
It was understandable why Miss Roberts's brother, Elgan, had been a murder suspect at one stage, said Miss Evans, but that line of inquiry had been considered and discounted.
She said: "But ultimately there's a very real danger of being tempted away from the central evidence.
"We say the cold, hard factual evidence is overwhelming and that evidence points in one clear direction."
Giving evidence, Mr Davies insisted that he did not kill Miss Roberts.