NEW WESTMINSTER - A defence witness who tested stains on a mattress that the Crown alleges are blood stains told the Robert Pickton murder trial Monday he is not a blood expert.
Gordon Ashby said his tests are almost always conducted on materials not related to human substances.
Ashby, the first expert witness called by the defence since it began its case last month, was qualified as an expert witness in the "identification of unknown substances through applied chemistry.''
Ashby, who has a diploma in chemistry from the B.C. Institute of Technology, conducted a series of tests using infrared spectroscopy and solvents on parts of a mattress that was seized by investigators in 2002 from a motorhome on Pickton's property.
His testimony was stalled momentarily when the Crown challenged his credentials.
Crown prosecutor Derrill Prevett said Ashby has limited credentials in testing for blood and other human substances.
But Justice James Williams rejected the Crown's argument and said Ashby could be questioned by the defence and any deficiencies the Crown felt relevant could be brought to the jury's attention through cross-examination.
In April, an expert witness for the Crown said DNA matching Pickton was found on some items together with DNA that matched some of the women he is accused of killing.
Lab analyst David Morissette, who has been reporting on DNA lab results for about two decades, said numerous swabs of stains taken from a mattress, some cider bottles, a running shoe, a kitchen counter, a beer can, a shower hose and syringe in the rear of the dilapidated, filthy motorhome yielded DNA that matched Mona Wilson.
For those matches, the chances of the DNA findings being someone other than Wilson were pegged at one in 26 trillion.
Pickton, 57, who was arrested in February 2002, is charged with first-degree murder in the deaths of Marnie Frey, Georgina Papin, Brenda Wolfe, Sereena Abotsway, Wilson and Andrea Joesbury.
He is also charged with 20 additional counts of first-degree murder and a trial on those charges is expected later.
Under questioning by defence lawyer Marilyn Sandford, Ashby said he went to the RCMP lab in August and took several samples of stained areas from a foam mattress that had been seized from the motorhome.
He also found a piece of foam from his home and, with the help of his wife, pricked his finger and placed a few drops of his blood on the foam.
He took samples of his own blood because in his company's database of substances, he estimated there are about 50,000 items, but none of them are blood.
By contributing his own blood sample, he had an example of blood to compare with his testing of the stains.
One test of the mattress samples he obtained indicated a polyurethane substance only; another test resulted in his finding what he called "de-foamers'' or substances associated with foam mattresses. Still other tests revealed substances like clay or dirt or talc, he said.
One set of tests revealed the presence of glue-like substances such as wood glue.
He also told the jury he detected a substance that resembled "blood glue'' and explained that some glues are made from animal blood.
Many glues, he said, contained nitrogen, as does blood.
"They are biologically and protein related,'' he told the jury of seven men and five women who began hearing evidence in the trial in late January.
Under cross-examination by Prevett, Ashby said the stains on the mattress did not resemble blood; it was not as dark a stain as his own sample.
"It didn't look like blood but I'm not a blood expert,'' he said.
He also conceded that a more appropriate test to detect blood would be DNA testing, which he didn't do.
Ashby said he had never used hemastix or hemochromogen, both well-known tests for the possible presence of human blood.
