Prosecuting lawyers have told the Court of Appeal that evidence about Tipperary farmer Patrick Quirke's behaviour before and after the disappearance of Bobby Ryan was entirely relevant to establish his motive for murdering the DJ, known as Mr Moonlight.
Quirke was convicted of murdering his 52-year-old love rival after a 15 week trial last year.
He had denied any involvement in the murder and said he uncovered Mr Ryan's remains while emptying an underground tank.
On the third day of the appeal, senior counsel Michael Bowman rejected arguments made by defence lawyers that they had introduced irrelevant evidence to the trial to paint or present Quirke in a certain way.
Mr Bowman said that "context was everything" in cases, including those involving circumstantial evidence.
He said the defence was arguing that all of the detail and the descriptive narrative of the life led by Mary Lowry should be taken out of the case. If this was done they would be left with the meaningless description used by the defence that "unhappy differences" had emerged between Mr Quirke and Ms Lowry.
This would have resulted in a manifest injustice to prosecution case and to Mary Lowry as a witness, Mr Bowman said.
He also argued that what happened after the disappearance of Bobby Ryan was entirely relevant and communicates motive in the first place, referring to recordings of Ms Lowry with a new partner Flor Cantillon which the prosecution said were made by Patrick Quirke. Mr Bowman said these were "like crumbs being left out to follow the mindset".
He said Mr Quirke's motivation was to remove Mr Ryan and to take his rightful place, as he saw it, as Mary Lowry's lover.
He rejected an argument that motive can only arise up to and until an offence is committed and said behaviour afterwards could strengthen and reinforce the presence of motive "that which communicates the true nature and extent of the relationship between the parties".
He said complaints from the defence about references to Patrick Quirke suffering from depression were introduced by Quirke who had referred to himself as "being in a bad place and receiving counselling". He said at no stage did the prosecution suggest he had a clinical diagnosis of depression.
There was no unfairness in detailing financial transactions between Mary Lowry and Patrick Quirke because Quirke had said he was under financial and workplace stress when he attended his GP in February 2011, Mr Bowman added.
He said Mary Lowry was a source of revenue for Quirke and it was reasonable to show the jury what he was likely to lose if he lost Ms Lowry. The suggestion by the defence that financial affairs were a red herring or a collateral issue did not stand up to scrutiny, he added.
Earlier defence lawyers said a search warrant used at the home of Patrick Quirke was defective and should not have been used to gather evidence against him.
Senior Counsel Bernard Condon said the warrant was defective and the application to secure it from a district court judge was inadequate to allow her to make a proper decision.
He said there was a failure by gardaí to inform the judge they intended to search for computer evidence, instead listing clothing, jewellery and a phone belonging to Bobby Ryan.
Mr Condon said the application for the warrant had used the district court as a "rubber stamp" exercise and the material obtained from Quirke's home was seized in an unconstitutional and disproportionate manner. He said the warrant itself was "barely intelligible if intelligible at all".
He said the application was made to the district court for the warrant on 13 May and the judge was not told that gardaí were planning to conduct a voluntary interview with Patrick Quirke on 16 May.
The warrant was executed and items seized from Mr Quirke's home early the next morning.
The appeal which is being conducted by video link is expected to conclude tomorrow. Patrick Quirke has been observing the hearing each day from Portlaoise Prison.