The young man at the centre of the weekend murder-suicide knife tragedy took his own life by stabbing himself in the heart, a post-mortem examination has revealed.

Student Shane Clancy (22) suffered the fatal wound after stabbing himself a number of times in the chest after he killed friend Sebastian Creane (22) and seriously injured two others, it has been learned.

The revelation is the latest shocking detail to emerge from the violent tragedy that has led to the deaths of two friends and left a young woman in critical condition in hospital.

Gardai are still trying to establish a firm motive for the savage attack. However, detectives suspect Clancy may have attacked Mr Creane in a row over a young woman, Jennifer Hannigan (22).

Ms Hannigan was being operated on in hospital last night after being stabbed in the back during the frenzied attack at the Creane family home in Bray, Co Wicklow, in the early hours of Sunday.

Mr Creane's brother Dylan (28), who was stabbed when he tried to tackle the killer, was also being treated at St Vincent's Hospital in Dublin. Gardai last night said both of their conditions were not threatening.

Neighbours yesterday confirmed Ms Hannigan and Clancy had gone out with each other for three years, but broke up six months ago.

Post-mortem examinations revealed that Mr Creane died as a result of stab wounds to the chest.

Clancy also had stab wounds to the chest, at least one of which pierced his heart.

Following the examination and an analysis of the scene, gardai are satisfied that all of the stab wounds Clancy suffered were self-inflicted in the back garden of the house.

It is thought he was kneeling when he stabbed himself and may have allowed himself to fall forward onto the blade.

The search by investigators for a firm motive to explain the attack has been hampered by the condition of the two victims in hospital, who they have been unable to interview.

A second woman who was also in the house at the time of the attack, but was not injured, rock guitarist Laura Mackey (27), has also been unable to do a full interview with gardai.

Ms Mackey, a member of Meteor Award-nominated band Boss Volenti, was described by officers as “suffering from shock and severely traumatised”.

“The investigation is being progressed. At the moment we are not speculating on a motive and we are still trying to piece together a full timeline of what happened,” a senior garda source told the Irish Indpendent.

Neighbours in quiet cul-de-sac numbed by deaths

Two friends, a broken relationship and a night of almost unimaginable horror, which resulted in the gruesome deaths of two young men and left two others fighting for their lives in hospital.

Neighbours in Cuala Grove were desperately trying to come to terms with the horrific bloodbath in the normally quiet, middle-class estate.

The parents of Sebastian Creane arrived back to their home in Bray late on Sunday, their holiday cut short in the most tragic circumstances.

The came home to discover their 22-year-old son was lying dead in a morgue after he was brutally stabbed to death in their family home.

Their son's killer was his friend, Shane Clancy, also 22. He then plunged a knife into his own heart before dying in the Creane's back garden.

Jennifer Hannigan, an ex-girlfriend of Shane's, was in hospital after having surgery to remove part of a knife from her back. A brother of Sebastian Creane, Dylan, was also injured.

So what exactly happened in the early hours of Sunday morning that could have resulted in such horror?

Gardai are exploring the possibility that the two former friends got caught up in a sort of ‘love triangle'.

Mr Clancy and Ms Hannigan had been in a relationship for three years, which ended six months ago and she had recently got together with Sebastian Creane, according to neighbours.

It is still unclear when Mr Clancy found out about their relationship and if something triggered the attack or if it had been pre-meditated.

The Creane's family home remained sealed off by gardai yesterday as they tried to piece together how the tragic events unfolded.

Forensic officers examined the family home for the duration of the day and were seen removing bags of evidence from the house.

Fingerprints were visible on a door to the front of the house as a blood stained curtain floated in the breeze.

The mood remained sombre as shocked neighbours struggled to make sense of the killings.

A devastated friend of Sebastian's arrived at the family home last night to place a wreath outside the gates.

“Seb was one of the nicest gentlemen I have ever met,” he told the Irish Independent.

Another neighbour, Myra Browne, said everyone living on the quiet cul-de-sac of Cuala Grove and its surrounds is “utterly devastated”.

Vice chairman of Bray Town Council, David Grant said people “are very numb at the tragedy”.