Shane Clancy, who carried out a murder-suicide in Bray seven weeks ago, was given a three-week supply of antidepressant medication by a pharmacy despite his doctor instructing he should only be supplied one week's dosage at a time because of a previous overdose.

In an interview with the Sunday Tribune, Clancy's father Patrick claimed that even though his 22-year-old son informed a doctor that he had taken three weeks' worth of drugs in one day, he was still prescribed with more antidepressants.

It is believed the Trinity student may have overdosed on the second batch of medication prior to murdering Sebastian Creane and then taking his own life.

Toxicology results which will determine the level of drugs in his system are due back in the next few weeks.

Two days after initially overdosing on his medication, Clancy went to see another GP and allegedly informed him about what he had done.

Despite this, Patrick Clancy claims the GP prescribed a different antidepressant but left a note on the prescription telling the pharmacist to only supply Shane with one week of the drug at a time.

When his son then went to fill the second prescription, the chemist asked him if he wanted to get the three-week prescription filled at once, and Shane said yes.

"I don't know if he was attempting suicide when he took three weeks' worth of antidepressants in one day. I might never know. I don't want to be seen as pointing the finger at the doctors or the chemist, but surely if it said to only give him one week's supply at a time, the chemist should have followed that instruction," Patrick Clancy said.

"I know in my heart and soul it was Shane's hand that took a life – but it wasn't his mind. I do not know how he got to that point. He spent 22 years on this planet as a wonderful, loving person. But people are now judging him on the last hour of his life… Shane put a high dosage of chemicals into his body and I've no doubt he reacted to that," Patrick Clancy added.