The jury in the trial of a man accused of murdering teenager Mariora Rostas may begin deliberating on a verdict tomorrow after a six week trial.

Mr Justice Patrick McCarthy has begun his charge to the jury which will continue tomorrow.

The 18-year-old Romanian girl went missing on 6 January 2008 after getting into a car while begging in Dublin City Centre.

She had been in Ireland for just 18 days.

Her body was buried in a shallow grave in the Dublin Wicklow Mountains where it was discovered four years later.

She had been shot four times in the head.

Alan Wilson of New Street Gardens in the city has pleaded not guilty to murdering Ms Rostas at Brabazon Street, The Coombe between 7-8 January 2008.  

His friend Fergus O'Hanlon has told the trial he helped him to bury the body.

Mr O'Hanlon had been arrested on suspicion of withholding evidence about the crime in 2008, but in 2011 when arrested on a separate matter, he told gardaí he had information about the girl's disappearance.

In closing arguments prosecuting counsel Sean Gillane has told the jury that the case involved a "journey through the heart of darkness".

He said the girl's murder was a cold, calculated and precise execution, after which every scrap of evidence had been meticulously, comprehensively and successfully destroyed.

He said in that context the evidence the prosecution relied on was "never going to be from an altar boy or a choir boy".

He said the jury would have to assess Fergus O'Hanlon's motivation for giving the evidence.

Mr Gillane said in 2011 despite being told by his solicitor that he could be prosecuted, Fergus O'Hanlon still wanted to assist gardaí to find the girl's body.

He said O'Hanlon's solicitor had made it clear there were no deals on offer for immunity and Mr O'Hanlon had not looked for it and did not need it.

He said in law Fergus O'Hanlon was an accomplice and the jury would be warned about the dangers of convicting on the uncorroborated evidence of an accomplice. 

However, he said there was corroboration to be found in the evidence about the ownership of the car, which was registered to the accused man Alan Wilson.

"The DPP invites you in the light of the evidence to find Alan Wilson guilty of the crime of murder".

He said "guesswork and speculation" leads to the wrong results.

Defence counsel Michael O'Higgins said in what was a one witness case the witness was a compulsive, manipulative liar, who could be connected to the crime more than his client.

He said the photofit of a suspect bore a striking resemblance to Mr O'Hanlon and he also had use of the car used in the crime.

He said the murder took place in Mr O'Hanlon's home in Brabazon street.

He said Fergus O'Hanlon had refused to take part in a formal identification parade, while his client was never put in an identification parade, despite being willing to participate.

The victim's brother viewed an informal identification parade, which included Fergus O'Hanlon, and while he did not pick him out he later said there was a man in the parade with similar skin to the man he saw driving the car that took his sister away.

Mr O'Higgins said Mr O'Hanlon had been interviewed 17 times about the disappearance of Ms Rostas and denied any knowledge.

He said it was only when arrested in 2011 on suspicion of conspiracy to murder a journalist he asked to speak to gardaí off camera and asked them to "do a deal".

He said he had benefited and continued to benefit from giving the information.

He received money while in the witness protection programme, he had been given immunity from prosection and gardaí had given evidence on his behalf in a district court case, which led to a suspended sentence.

Mr O'Higgins said he openly stated his hatred for Alan Wilson in an interview with gardaí.

He also had an unhealthy relationship with women and was volatile, controlling and uncontainable if he did not get his own way.

Mr O'Higgins said Fergus O'Hanlon had repeatedly told lies in the witness box, which the defence was able to prove through uncovering records.

He said it was a one witness case and it came down to whether or not they could be sure he was telling the truth beyond a reasonable doubt.