Graham Dwyer's murder trial has heard paint spots found on a spade near Elaine O'Hara's remains did not match paint samples taken from his home in Foxrock.

Yesterday, the architect's wife Gemma Dwyer identified the spade as being the same as one missing from their garden.

In her evidence yesterday Gemma Dwyer was shown a photograph of a spade found near Elaine O'Hara's skeletal remains at Killakee in the Dublin mountains.

She said she recognised the spade as one missing from their home partly because there were splashes of paint on it from the painting of a garden fence.

Today Bridget Fleming from the Forensic Science Laboratory gave evidence that she analsyed the spots of brown paint on the spade with paint samples and a piece of the timber fence at the Dwyer's address in Kerrymount Close.

She said while they were similar in colour she observed differences in their chemical composition and concluded they did not match.

Graham Dwyer denies murdering childcare worker Elaine O'Hara at Killakee mountain in August 2012.

Earlier the Central Criminal Court heard a DNA profile matching Graham Dwyer was found in stains on Elaine O'Hara's mattress.

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 5 areas of semen.

The jury heard DNA profiles matching the accused Graham Dwyer were found on 3 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.