The prosecution claims Graham Dwyer very nearly committed the 'perfect murder' when he allegedly killed childcare worker Elaine O'Hara.

The architect with an address at Kerrymount Close, Foxrock is accused of stabbing the 36 year old for his own sexual gratification.

Opening the case prosecution counsel Sean Guerin claimed Elaine O'Hara was 'almost the perfect victim'.

The 36 year old suffered from a psychiatric illness and there would be every reason to believe that her death was a suicide.

Mr Guerin said it's highly unlikely that her belongings would have been found in the Vartry reservoir in September 2013 if the water levels had not dropped so low after the hot summer.

It is the prosecution's case that text messages between a number of phones, including two mobiles found at the reservoir, are evidence that Elaine O'Hara was the extremely submissive partner in a sado-masochistic relationship with Graham Dwyer that involved stabbing.

They claim he killed her for his own sexual gratification. Graham denies murder.

The jury has spent the afternoon listening to technical garda evidence.

The jury has been told Elaine O'Hara's skeletal remains were found by a dog walker up the Dublin mountains more than a year after her disappearance.

Opening the case at the Central Criminal Court, prosecution barrister Sean Guerin has told the court it is alleged that there was phone contact between the two in the run up to her death.

One of the texts read out in court said 'my urge to rape, stab, kill is huge..you have to help me control or satisfy it'.

It is also alleged that they had an unusual relationship which featured acts of stabbing by Graham Dwyer on Elaine O'Hara.

The prosecution claims there is CCTV footage of Graham Dwyer at Elaine O'Hara's apartment block in Stepaside and that there is evidence semen found on her mattress is his.

Courts correspondent Francesca Comyn spoke to Lunchtime about the case: