Murder of Elaine O'Hara

Elaine O'Hara was a 36-year-old childcare worker from Dublin, Ireland. She had a history of mental-health difficulties. On 22 August 2012 she was last seen at Shanganagh Park in Shankill, south of Dublin; her car was found nearby, and because of her history she was initially presumed to have taken her own life. No trace of her was found for more than a year.

In the summer of 2013, an unusually dry spell lowered the water level at Vartry Reservoir in County Wicklow. Items recovered there — including handcuffs, restraints, a knife, an inhaler and two mobile phones — were later linked to O'Hara. In September 2013, skeletal remains were discovered in a forested area at Killakee in the Dublin Mountains and were identified as O'Hara through dental records. Only part of her skeleton was recovered.

Investigators reconstructed a hidden relationship between O'Hara and Graham Dwyer, a Dublin-based architect. Data recovered from the phones and computers showed years of messages in which Dwyer expressed violent sexual fantasies, including explicit statements about a desire to stab a woman to death. Prosecutors argued that the two mobile phones found in the reservoir had been used almost exclusively to contact one another, and that a message sent on 22 August 2012 directed O'Hara to the shore where she was last seen alive.

Dwyer was arrested and charged with murder. His trial opened in January 2015 and became one of the most closely followed criminal cases in Irish history. The prosecution presented the digital messages, videos, forensic findings and mobile-phone location evidence as proof of a deliberate plan to kill. The defence argued that the cause of death could not be established and that the case was circumstantial. On 27 March 2015, a jury unanimously found Dwyer guilty of murder, and he was sentenced to life imprisonment.

Dwyer pursued a lengthy series of appeals, focused largely on the legality of the mobile-phone metadata used against him. While the Court of Justice of the European Union found that Ireland's indiscriminate retention of such data was inconsistent with EU law, the Irish courts held that the evidence had been properly admitted. The Court of Appeal rejected his challenge in March 2023, and on 31 July 2024 the Supreme Court unanimously dismissed his final appeal, ruling that the evidence he had met O'Hara on the evening of 22 August 2012 in order to kill her was overwhelming. The decision exhausted his options within the Irish legal system, and he continues to serve his life sentence.