UPDATED 12.08pm: An ESR forensic scientist had concerns blood found on the floor of the Lundy home, was brought there on the shoes of investigators.

Lundy, 56 is charged with the August 2000 murders of his wife Christine and daughter Amber.

He was convicted of the murders in 2002, but that conviction was quashed by the Privy Council, and is now facing a retrial in the High Court in Wellington.

Bjorn Sutherland has been giving evidence in the retrial – and was this morning questioned about blood found through chemical testing.

Defence lawyer David Hislop, QC, referred to a communication between Bjorn Sutherland and police.

Mr Sutherland said he was worried some blood might have been from investigators.

"I had a concern they might have been due to our footwear contacting some spots of blood, or blood staining on the floor after we had pulled up the stepping plates."

He said the vague luminal positive areas didn't have any verifiable patterns, so they couldn't be traced.

Mr Sutherland said the luminol testing was carried out after the majority of blood samples had been collected from the crime scene.

Earlier David Hislop asked about paint flakes found in debris, including blood, hair and traces of bone, from around Christine Lundy.

The orange and blue flakes are the same colour paint as that on Mark Lundy's tools.

Mr Hislop asked Bjorn Sutherland if the flake paints in the house could’ve been there from previous tool use, or from someone bringing them in from the shed, on their shoes or clothes, before the murders.

Mr Sutherland said he certainly couldn’t exclude that. Court has now adjourned for the day.