Lawyers give final summing up at teen murder trial

Mr Costigan has pleaded not guilty to the murder of Christine Quinn at her home on Greenfields Road in the city on December 5, 2002.

Mr Owens told the jury that there was a "compelling case against this accused".

He said the first matter was that Mr Costigan had not been in the Quinn house since September 2001 due to a falling out, yet various items of forensic significance linked him to the house in December 2002.

Secondly, he said, up to the falling out, the accused had been a frequent visitor to the home; "He knew the lie of the land. Also, he knew he had a means of access over the back wall".

Mr Owens reminded them of the two sightings of Mark Costigan in the vicinity on the afternoon of the murder. Two schoolgirls had met him in the city about 1.30pm.

He was on his own and walking out of town in the direction of Greenfields Road. As he drove away from the Quinn house about 15 minutes later, Mrs Quinn’s partner, Paul Byrne, had seen the accused alone and walking in the opposite direction.

It was also important, the State said, that Mr Costigan had a half day from school that Thursday and that his teacher, Olive Keyes, had noticed nothing wrong with his hands that morning.

The following day, he came into school at 11am, when another teacher, Mandy Bloomer, noticed he was wearing a bandage on his hand and unable to write. The accused had given various explanations to friends and the gardaí about this hand-injury, including that he had hurt it playing soccer and on a jigsaw in Woodwork class.

But, the defendant’s Woodwork teacher, Mr Tierney, had told the court electric saws were not being used in his class that semester. "The cut hand had nothing to do with Mr Tierney’s class and everything to do with what went on at 2 Greenfields Road" declared Mr Owens.

The prosecution also pointed to the teenager’s "suspicious" behaviour hours after the victim was stabbed to death.

At 5.25pm, he was seen "lurking at the door" of Gamesworld before going in, he said. Referring to CCTV footage from the shop, Mr Owens pointed out that the accused’s right hand was covered with something and that "this right-handed boy was not using his right hand at any stage in that shop".

The tendering of the bloody €50 note and the boy’s bloodstained clothing were also mentioned.

"Some evidence cannot tell any lies," Mr Owens told the jury. He said there was not any more credible evidence that Mr Costigan’s injury had occurred by that evening than the Gamesworld video.

He acknowledged that it "may be a bit of a leap to suggest the €50 had been taken out of the wallet, but you’ve heard the shopping that was done that morning". Mr Owens was referring to a wallet found at the scene, which contained €100 less that evening than it contained in the morning, and to a small amount of groceries the victim bought before lunch.

The prosecution highlighted evidence heard that the accused had sold his Playstation 2 three months before the killing, but that shortly afterwards he once again had a Playstation 2, telling the gardaí he had it for years.

Mr Owens said the jury could draw an inference from this that Mark Costigan had taken it from the Quinn home. He reminded them that Jason Quinn had identified a "peculiarity" on his game as matching the one taken by the gardaí from the accused’s home.

The prosecution then moved on to what he described as the "silent witness" - forensic evidence. He reminded the jury of the broken clock found at the scene, which was stopped at 2.54 and covered in soot.

Counsel pointed to the State Pathologist’s view that there would have been a struggle. He believed this is why the teenager broke the knife he jammed into the victim’s head and when he had injured himself.

Blood matching Mark Costigan’s DNA was found upstairs on a doorknob of a back bedroom. The same DNA was found in blood on a duvet cover and a soccer jersey in a front room.

An exact match of the accused’s DNA was also found on the stair banister. The only credible conclusion, Mr Owens said, was that after killing Christine Quinn, Mark Costigan went upstairs and into the back room, touching the door handle.

He then went into the front bedroom, he said. "He did this to look out the window to see if the coast was clear," said Mr Owens.

Finally, said Mr Owens, "Right handed Mark Costigan, coming down the stairs, dripped blood onto the right banister."

Mr Owens concluded that all of this evidence led to one explanation; the guilt of Mark Costigan. He said "the case against Mark Costigan is well and truly proved. If the prosecution case is not true, Mark Costigan must be the unluckiest man in Ireland to have all this evidence stacked up against him."

In the defence’s closing speech, Mr Paul Coffey, SC, said the resources of the State were not available to the defence.

He said 11 areas of high variability were examined in the DNA evidence and that there were hundreds of other areas that were not looked at. He said everything must match and that it was "simply not good enough to speculate… it can only give rise to a reasonable doubt".

Mr Coffey also criticised DNA itself, saying "it purports to be a theory of likelihood". He said it was not imperial, not based on experience and dismissed it as "simply an invention".

He also pointed out that science can sometimes be wrong and said "there’s always the possibility of laboratory error".

Mr Coffey also addressed the lack of motive. He said his client had not been at the Quinn house in 16 months, and asked what would have inspired him to go there on December 5.

He said the argument in September 2001 about a mobile phone was hardly a question of war and peace that could lead to such "gruesome brutality".

He said: "If Mark Costigan is the homicidal maniac he’s being made out to be, he was so on the morning of the fifth and he was so on the evening of the fifth".

He pointed to evidence of various acquaintances who had noted nothing unusual about his client that day.

Finally, Mr Coffey noted the lack of his client’s blood and DNA on the murder weapons. He said if he wielded either knife while he was bleeding, his blood would have come into contact with the weapons.

He mentioned Dr Marie Cassidy’s opinion that there would have been a considerable transfer of blood from Christine Quinn to the attacker.

He submitted that such a transfer was not consistent with his appearance that evening and that his mother, who did his laundry, had never come across anything that caused her concern.

Both sides have now finished their summing up and Mr Justice Michael Peart will begin his charge to the jury tomorrow morning.