Closing speeches have finished in the trial of a 50-year-old farmer, accused of the murder of his alleged love rival in Tipperary.

Patrick Quirke of Breanshamore in Co Tipperary, has pleaded not guilty to murdering Bobby Ryan, a part-time DJ known as Mr Moonlight.

Mr Ryan went missing on 3 June 2011 after leaving his girlfriend Mary Lowry's home.

The prosecution claims Mr Quirke murdered Mr Ryan so he could rekindle an affair with Ms Lowry.

Prosecution and defence speeches are now over. The jurors will return to court next Tuesday when the judge will summarise the evidence and direct them on the law before sending them out to begin deliberating.

On the third day of his closing speech, Defence counsel, Bernard Condon, told the jurors they could not convict someone on the basis of computer searches.

He said there was no "hard evidence" that Mr Quirke had murdered Bobby Ryan.

Mr Condon asked the jury to apply fairness when considering Google searches conducted on Mr Quirke's computer for information about human decomposition.

The searches took place months before Mr Ryan's body was found in an underground tank on the farm in Fawnagown in Tipperary Mr Quirke was leasing from his former girlfriend, Mary Lowry.

Mr Condon said the jurors should be aware of the substantial limitations of the computer evidence. 

He said they could not say the searches were linked to the murder case and there was a great risk of making an enormous leap. He said the height of the prosecution's case was that the searches were suspicious. 

"People do the strangest things on computers," he told them "this is just a fact of life". 

He said if Mr Quirke was the killer as alleged by the prosecution and had wanted to know what condition the body was in, he could have just lifted the lid on the tank to look.

He also referred to searches of the RTÉ website for news about Mr Ryan.

Mr Condon said he didn't think there was a person in Tipperary who didn't look up Bobby Ryan.

Mr Condon also suggested a note made on a piece of A4 paper found in Mr Quirke's house was of very little relevance to the case. 

The prosecution suggested the note was written before Mr Quirke was questioned by gardaí in April 2013 and some of what was written was consistent with his answers in that interview. But Mr Condon said it was more likely it was written afterwards. 

There were a number of questions about Ms Lowry on the note. Mr Condon asked why Mr Quirke wouldn't be suspicious of Ms Lowry. 

And he said the jury might say Mr Quirke was a nosey parker, but that was a very long way from finding him to be a killer.

Mr Condon urged the jury to approach the prosecution case with scepticism, to test it, evaluate it and see if it passed the test of "beyond reasonable doubt".

He said the jury was a safety mechanism for all citizens - their role was not to pass theories which were not proven. If they passed the prosecution theory about this case, he said, it could have very profound consequences and that was why the burden and standard of proof were so high.

Mr Condon said the prosecution suggestion that someone had taken the time to make sure no forensic trace was left behind, was "wild speculation" and should not be adopted by the jurors "willy-nilly".

A key portion of the case - what happened to Mr Ryan, was not there, he said.

The prosecution alleged this was a planned killing, and yet, Mr Condon said, a beating was administered to Mr Ryan without being heard, his body was removed from the scene, stripped, placed in a tank, the blood cleaned, all done in a very short window - according to the prosecution.

Mr Condon said the inferences the prosecution was asking the jurors to draw did not move the train, "parked in innocence station", very far in terms of proving a case of murder.

He said the jurors were being asked to make a very important decision on circumstantial evidence. Without hard evidence, he said, they had to be sure that they had the full picture.

He said the manner in which someone died was relevant.

The prosecution's preferred theory was that Mr Ryan had been killed by blunt force from an instrument - but they had no nominated weapon which could have been used.

He said the jurors had heard evidence from two eminent pathologists - one of whom preferred blunt force trauma from an instrument as the cause of death but did not rule out injuries from a vehicle, the other preferred injuries from a vehicle, but did not rule out the trauma being caused by a weapon.

Mr Condon said the defence was absolutely entitled to test the evidence.

And it was surprising the prosecution seemed to be frustrated and seemed to suggest the defence or the jury should just accept the prosecution analysis.

Mr Condon also referred to a woman's tortoiseshell hair clip found in the tank where Bobby Ryan's body was discovered.

He said the prosecution had pooh-poohed this evidence.

But he said he was asking the jurors not to. He said the jurors had to be sure the hair clip was legitimately excluded from the case and did not amount to reasonable doubt.

Mr Condon's speech concluded this afternoon.