Lawyers for Armagh man James Flynn (31) have argued that he shouldn't be extradited back to Ireland due to a delay in the prosecution.
Gardaí want to charge him with robbery at Lordship credit union, Dundalk, in January 2013 as well as conspiracy to commit six burglaries.
Detective Garda Donohoe was shot dead when he and a colleague were ambushed by a five-man gang while on an armed escort.
During today's hearing, James Flynn said he was suffering from a panic attack, while the father of convicted killer Aaron Brady also gave evidence as part of an abuse of process application which was refused.
Graeme Hall, barrister for Mr Flynn, argued that the extradition of his client would be unjust due to the passage of time, and because the allegations against him have not been particularised.
He said there was medical evidence that his client's memory is now "significantly and adversely affected" and that he can't recall what took place in 2012 and 2013.
The court was also told he had a relapse in his PTSD and that the extradition would likely lead to a further deterioration in his mental health.
Amanda Bostock, for the Crown Prosecution Service (CPS), said that the delay was due to the complexity of the case which included over 6,000 lines of inquiry and 3,200 statements.
She said there is nothing to suggest Mr Flynn's PTSD was worse than at the time of the robbery, and that he gave statements to police on three occasions in 2013 when his account was "fresh in his mind".
Another reason for refusing the request, Mr Hall said, was that the specific offences his client was accused of aren't set out in the extradition warrant.
He said there had been a "broad omnibus description" of the charges but that there was no specific understanding of the case against James Flynn.
Ms Bostock said that the case was one of joint enterprise and that they did not have to prove exactly what role Mr Flynn allegedly had in the offences.
It was the prosecution's case, she said, that Mr Flynn was in the credit union car park and participated in the robbery, and was part of the group that committed the burglaries.
The presiding judge, sitting at Westminster Magistrates' Court, said he would deliver a ruling on the extradition request later this month.
Before the hearing began this morning James Flynn asked for an adjournment to seek fresh representation and on health grounds.
"This is going on for nine years, this is my life your honour," James Flynn said, adding that he had little contact with his solicitors.
He also said he was having a panic attack in court citing his heart "beating out of my chest", that his hands were changing colour and that he hadn't slept in three days.
Refusing the adjournment, the presiding judge said: "You appear to me well composed and making an impressive job of putting across what you want to say."
His legal team had also made an application to have a stay put on proceedings because the prosecution amounted to an abuse of process.
From the witness box Mr Flynn said he had spoken to investigators on three occasions but that he was one of "thousands of people" spoken to.
He told the court he had no worries "in the slightest" about being prosecuted for "something I didn't do" and claimed a "case of lies" was being built against him.
Tony Brady, the father of Aaron Brady who is currently serving a life sentence for the capital murder of Adrian Donohoe, was also called to give evidence.
He said he has "serious concerns" about the investigation, that there were "glaring issues" in the case and that relevant CCTV footage was missing.
In particular, he said, this related to footage near a south Armagh yard where Aaron Brady claimed he was laundering diesel at the time of the murder.
When questioned further he said he could not say 100pc if that footage was watched by the defence or reports relating to it were disclosed.
Ms Bostock said that the Irish courts considered the trial safe and that the High Court judge would have been aware of these alleged issues when signing the extradition warrant.
The presiding judge said he could find no conduct here "capable of amounting to an abuse of process in respect of the extradition courts process".