The final Crown DNA expert testified that Travis Vader's DNA was almost certainly on the sweatband of a baseball cap found in Lyle and Marie McCann's SUV.
The witness was the third and final Crown's DNA expert who testified Tuesday morning.
Janice Rae Lyons, who works as a reporting scientist in the RCMP's forensic laboratory in Edmonton, gave evidence about tests she had done on exhibits from the McCann investigation as early as December 2011 and as recently as August 2014.
In August 2014, she did an analysis of a sample taken from the sweatband of a “Vokap” baseball cap found on the floor in front of the front passenger seat of the McCanns’ green Hyundai Tucson, and concluded the DNA found matches a known sample of Vader's DNA, with a probability of a random sample from a random Caucasian Canadian being one in three trillion.
Samples were taken from several other portions of that hat, none of which yielded any type of match.
The Vokap hat is the second of two hats found in the SUV. A previous DNA expert testified about a sample collected from a “Baug Draught” baseball hat found on the floor behind the driver seat.
The Baug Draught hat, which had apparent blood stains and a bullet hole in the brim, had one mixed DNA sample containing a match to Lyle McCann's sneakers, with a one-in-three-trillion chance of a random match, and also a match to a known sample from Vader, with a one-in-140,000 chance of a random match.
Lyons testified she also did an analysis of the Baug Draught hat, from another location on the hat, finding a match to Lyle McCann's sneakers, similarly with a one-in-34-billion chance of a random match, but she did not report finding any match to Vader's DNA.
Lyons also testified about analyses done on several other items, including food cans found in the SUV. Her tests also showed the blood on the food cans matched a sample taken from Marie McCann's hairbrush, with a one-in-4.6-trillion chance of a random match.
She also testified there were samples of Travis Vader’s DNA on several clothing items – a pair of coveralls, a pair of shorts, a pair of track pants and a golf shirt – found at a tent site at which Vader is believed to have lived while on the run from police.
The probability of a random match is one in 2.7 billion on the coveralls, one in three trillion on the track pants, one in 28 billion on the shorts and one in 180 million on the golf shirt.
In his cross-examination, defence lawyer Brian Beresh focused mostly on the same areas he had with the previous DNA expert witnesses.
Lyons said it was unlikely but possible other scientists in other labs could come to different conclusions based on the same samples, that there was no way of testing when or how a sample was deposited, and that while unlikely, secondary or even tertiary transfer of genetic material is possible.
“The most likely explanation for DNA being on an exhibit is a direct transfer, but I can't rule out an indirect transfer,” she said.
Beresh focused more specifically on the Vokap hat, and specifically suggested given how testing is done, with material sampled from an area like a sweat band of a hat, it's impossible to tell exactly where that material came from.
She also testified that many of the exhibits she examined were being examined for the second, third and even fourth time.
Crown prosecutor Jim Stewart said he had a few questions following the cross-examination after the lunch break.
After that, a firearms expert is expected to testify about the bullet hole found on the Baug Draught hat, and time permitting an RCMP officer will begin his testimony about evidence handling.
On Monday afternoon, court briefly heard the continuation of Beresh's cross-examination of Vivian Mohrbutter, the second DNA expert to testify.
Beresh had asked her about rework done on a specific sample, which came from the Baug Draught baseball cap, noting it was suspicious the sample was found to match Vader not in initial tests but in subsequent tests.
Stewart addressed this, with Mohrbutter explaining a new technique was used in the rework that hadn't been available during the initial analysis, and that new techniques are often added to the kinds of tests available at the lab as they're developed.
“Was this rework method invented by RCMP to tie exhibits to Travis Vader?” Stewart asked.
“Ha, no,” she replied, explaining decisions about protocols and procedures are made independently of any specific analysis or samples scientists may be working on.
