Stains on Mark Lundy's polo shirt could be food that contained brain or spinal cord cells, a professor who worked on victims of mad cow disease told a court today.
The dark shirt with yellow stripes is once again under the spotlight in the double-murder jury trial in the High Court at Wellington today.
The jury of five women and seven men were told yesterday by both prosecution and defence witnesses there was no doubt the cells contained central nervous system (CNS) cells, that could have come from the brain or spinal cord.
But it was not known whether the cells were human or not.
The Crown's case is that the stains on the shirt's pocket and left sleeve contained brain cells from Lundy's 38-year-old wife, Christine.
Lundy, 56, has denied killing her and their 7-year-old daughter in their Palmerston North home in the early hours of August 30, 2000.
Defence witness James Ironside, a professor of clinical neuropathology at Edinburgh University, gave evidence today.
In the early 1990s, he carried out the first autopsies of victims of Creutzfeldt-Jakob disease (CJD), which is associated with mad cow disease.
He told the court today the CNS cells could have come from food contamination.
"Foodstuffs and particularly meat products have been shown to contain CNS tissue if it is made in a particular way."
He pointed to products such as lamb chops sold in some butcheries that could have CNS cells in them.
Tissue that was necrotic -- or had dead cells -- and was unable to be identified, had been dabbed off the top of the CNS cells.
That gave weight to the theory that the CNS was contamination because it was such a different structure to the cells on top of it, Prof Ironside said.
Under cross-examination by prosecution lawyer Philip Morgan, Prof Ironside agreed there was no way of definitively knowing where the tissue came from.
Mr Morgan suggested both tissues were probably CNS tissue because otherwise it would mean the CNS tissue landed on the shirt and another type of tissue landed on top of it and was then cleanly wiped off to be tested.
Prof Ironside said it was one possibility, but there could be others.
"Don't you think that's too silly for words? What other explanation is there?" Mr Morgan asked.
Prof Ironside said he did not think it was silly because one of the tissues was necrotic while the other wasn't.
"I find it difficult to understand how they can be related to the one tissue."