The amount of drugs administered by medical staff to Jozef Puska before he allegedly admitted to murdering Ashling Murphy would have had no impact on his behaviour or his ability to communicate, a professor of pharmacology has told the Central Criminal Court.
Professor Michael Ryan told the trial that he has "never heard of anyone confessing to murder or anything of that kind" after taking the kind of low therapeutic doses of the painkilling drug oxycodone administered to Mr Puska at that time.
Mr Puska (33), with an address at Lynally Grove, Mucklagh, Co Offaly, has pleaded not guilty to murdering Ms Murphy at Cappincur, Tullamore, Co Offaly on January 12th, 2022.
Professor Ryan told Anne-Marie Lawlor SC, for the prosecution, that he is a professor of pharmacology and toxicology, and has worked in that area since 1969.
He studied the "extensive" medical files relating to when Mr Puska was taken by ambulance to St James's Hospital in Dublin on January 13th, 2022, until he was discharged on January 18th.
Ms Lawlor said the professor was asked whether the drugs administered to Mr Puska during that time had any impact or bearing on his making alleged admissions to gardaí shortly after 6pm on January 14th.
The prosecution alleges that while in a hospital bed in St James's, Mr Puska admitted to murdering Ashling Murphy by saying: "I did it, I murdered, I am the murderer," and by telling another garda that he "cut" Ashling.
Prof Ryan said it is his expert opinion that the drugs administered to Mr Puska at that time would have had "no influence" on his behaviour.
Prof Ryan said that, in coming to his conclusion, he looked at all the relevant medical documentation and detailed the doses administered of each drug, the half-life of each drug and the possible side effects.
Operation
He noted that Mr Puska had undergone an operation on January 13th to treat three puncture wounds to his abdomen, which finished at about 10.45pm. The surgery was carried out by keyhole incision, he said, and the injuries were described as minor or superficial.
By 6pm the following day, Prof Ryan said the anaesthetic and all other drugs administered before surgery would have been out of his system.
Mr Puska was given 5mg of oxycodone – an opioid similar to morphine that is used for pain relief – on four occasions from 3.32am until 4.05pm on January 14th.
Prof Ryan said he looked at all the published papers relating to the use of oxycodone and its possible side effects.
The dosages given to Mr Puska, he said, were at "absolutely the lower end of the scale" where people at the "very high" end could receive up to 400mg per day.
Considering the rate at which oxycodone breaks down in the body, he said the maximum amount that Mr Puska could have had in his system after 6pm that day was 8.25mg.
The scientific literature, he said, shows that dosages of below 10mg have "no effects on mood or behaviour" and it is only at higher doses that some side-effects would begin to be seen, he said.
Drugs such as paracetamol and ibuprofen, which were also given to Mr Puska, have no impact on the central nervous system, he said, and therefore would not affect behaviour.
The professor described the conditions in the hospital as a "highly controlled medical environment" in which Mr Puska was "monitored very closely" by medical professionals including nurses and a physiotherapist.
They noted throughout Mr Puska's time in hospital that he was "alert and orientated" and had "no impairment in sensory perception".
Prof Ryan said there were no signs of dizziness and no mention of any problems or issues with Mr Puska while he was taking oxycodone during that period.
He said the dosage of oxycodone administered was "at the very low end of the therapeutic range" and there was "no evidence to support that his admission was related to the effects of oxycodone... or any drug."
Prof Ryan said oxycodone would not have impacted on Mr Puska's memory function, and he was noted by medical professionals to be "alert and awake".
His oxygen levels were at 100 per cent saturation, which the professor said indicated there had been no impact on the respiratory system, a key side-effect of oxycodone.
Medical notes
Under cross-examination, Prof Ryan told Seoirse Ó Dúnlaing BL that he is not a consultant in intensive care or emergency care, and he has no experience treating patients on wards.
He said he focused on the effects of the drugs administered and on the medical notes in writing his report, but felt it was not his expertise or duty to interpret garda statements relating to Mr Puska's time in hospital.
Mr Ó Dúnlaing said gardaí reported that one of the machines monitoring Mr Puska went into alarm at one point while gardaí were present, but that was not recorded in the hospital notes. He asked if that gave Prof Ryan "pause to consider that not everything was recorded in the [medical] notes".
Prof Ryan said the medical notes were "extensive", adding: "I didn't feel it my responsibility or function to look at garda records."
Prof Ryan said he could not remember reading the note of Det Gda Fergus Hogan, who said Mr Puska did not recognise him despite having spent considerable time with him earlier on the same afternoon.
Mr Ó Dúnlaing asked if it struck Prof Ryan as "abnormal that he didn't remember speaking to the garda", to which he said it did not as Mr Puska was probably in a stressful situation following his operation.
Prof Ryan said he is not an expert on what effects that might have, but from his expertise, he could say that the oxycodone had "no possible effect" on Mr Puska.
Under re-examination, Prof Ryan told Ms Lawlor that it has never been recorded anywhere that a dosage of less than 10mg would impact a person's ability to communicate. He also agreed that he had "never heard of anyone confessing to murder or anything of that kind after taking 5mg doses".
Mr Justice Tony Hunt told the jury to return on Wednesday to hear evidence from the prosecution's final two witnesses. He said there is one legal issue to be dealt with and "other legal business has to be tidied up".
The trial continues before Mr Justice Hunt and the jury of nine men and three women.
