Gardai searched behind electrical fittings and wall cavities in convicted-killer Graham Dwyer's home for an electronic memory card which they believe contained horrific material, a new book on the murder of Elaine O'Hara reveals.
Working in consultation with a trained garda psychologist, detectives believe the memory card still exists and said they will continue to try to find it.
The book reveals that the assumption is based on an analysis of a sordid story entitled Killing Darci, which was found along with other disturbing material that proved Dwyer's fascination with knives, blood, rape and murder.
The shocking material had been deleted but was recovered by garda computer experts on a hard-drive seized during a search of Dwyer's Foxrock home.
Videos of the 42-year-old married father of three stabbing women, including his victim, while having sex, were also recovered on storage devices.
The revelations are contained in an explosive new book on Ireland's most notorious murder by veteran crime writer Paul Williams, which is being serialised today in the Irish Independent and tomorrow in the Sunday Independent.
Almost The Perfect Murder tells the complete inside story of the disturbing case that shocked the nation, and the extraordinary garda investigation that unmasked Dwyer and brought him to justice.
Williams also reveals the belief among detectives that Dwyer filmed the childcare assistant's murder when he lured her to Killakee Woods, in the Dublin Mountains, on August 22, 2012.
The writer interviewed several former close friends and colleagues of Dwyer, who hid his secret predilections from his wife and family.
They revealed a number of behavioural quirks and incidents that, with the benefit of hindsight, were signs of his darker side.
The book also details Dwyer's ability to manipulate vulnerable women whom he met online.
One of them, young US woman Darci Day, would prove critical as a witness for the prosecution, as Dwyer knew only too well.
And it sets out how a Christmas card Dwyer sent to Day proved to be vital to her providing evidence.