A DNA profile matching Graham Dwyer was found in stains on Elaine O'Hara's mattress, the Central Criminal Court has heard.
The 42-year-old architect from Kerrymount Close, Foxrock is charged with the murder of the childcare worker in August 2012 at Killakee in the Dublin mountains.
Dr David Casey from the Forensic Science Laboratory carried out DNA analysis on items from Elaine O'Hara's apartment including a rope, a rug, a gas mask and a black dress.
The results he said were mostly inconclusive - except for on a mattress where he found five areas of semen.
The jury heard DNA profiles matching the accused Graham Dwyer were found on three of those areas, along with blood stains matched to Elaine O'Hara.
He also examined items found near Elaine O'Hara's remains - including tracksuit bottoms and a spade, but they did not yield sufficient biological material for DNA analysis.
He said vehicles seized from Graham Dwyer's Foxrock home were extensively searched for blood using a chemical spray that detects trace elements, but no blood was found.