Lundy trail: Yorkshire Ripper scientist's testimony

Officers coming and going from the Lundy household during their crime scene examination could have contaminated or lost evidence, an overseas forensic scientist told a court today.

Mark Lundy's defence team has brought in the expert from the United Kingdom to give evidence at his double-murder trial in the High Court at Wellington.

He has denied killing his 38-year-old wife Christine and 7-year-old daughter Amber in the early hours of August 30, 2000 in their Palmerston North home.

Gillian Leak has worked on numerous murder scenes, including those of serial killer Peter Sutcliffe, dubbed the Yorkshire Ripper, who was convicted of murdering 13 women and attempting to kill another seven during the 1970s and early 1980s.

Mrs Leak, giving evidence for the defence, said the killer could have left from a conservatory sliding door, which was used by officers as they moved in and out of the house.

It was a good location for "forensic interest" as the killer could have left fibres or fingerprints there, she said.

People going in an out could have contaminated the area or damaged evidence, she said.

Police should also have been wearing full protective gear as soon as they entered the property, rather than changing into the gear while on the property, but before entering the house.

A little-used front door would have been a better route to come and go from, Mrs Leak said.

Defence lawyer David Hislop asked if a smear of Mrs Lundy's blood found on an open conservatory window could have been transferred there accidentally.

"I don't think anyone can rule that out," Mrs Leak said.

She also criticised the use of fabric overalls as protective wear, which were more inclined to pick up trace material.

As Mrs Leak was shown a video of police conducting their investigation throughout the Lundy house, she noted it would have been difficult for officers to move on stepping plates around Amber's body, which was lying partly across the hallway.

"It's actually quite narrow, you're actually stepping over the left arm to get from one stepping plate to the next."

Mrs Leak also told the court about how she believed the attack happened.

There was a mark on Mrs Lundy's headboard that did not have any blood embedded, meaning that would have happened early on in the attack, she said.

Mrs Lundy would have started off on her left side on the bed, but then turned onto her back later in the incident.

The trial in front of Justice Simon France continues.

By Rebecca Quilliam of NZME. News Service