DNA from a man and a woman accused of trying to murder Haines Junction RCMP Cpl. MacKellar was found at two crimes scenes, the Yukon Supreme Court heard Thursday.

Lab scientist Michelle Fisher testified some of the DNA found on the safe in front of Madley's General Store matched the DNA of 22-year-old Jessica Johnson.

The odds it was match for somebody other than Johnson are astronomical, she said.

Fisher said some of the DNA on the lever of the rifle discovered by the police dog near the Pine Lake Campground outside Haines Junction matched the DNA of 32-two-year-old Chris Cornell. Odds are something like one in 440 million it was a match for somebody else, she said.

Cornell and Johnson were charged on Sept. 26, 2011 with trying to murder MacKellar and deputy conservation officer Shane Oakley by shooting at them with a rifle during a high-speed chase along the Alaska Highway.

They were also charged with using violence on custodian Frank Parent and spraying him with bear spray while robbing or attempting to rob Madley's store.

Only Cornell is on trial at this time. The nine women and five men of the jury began hearing evidence last week.

This morning began with testimony from a firearms expert who examined a rifle, clothing, bullets and other material at her RCMP lab in Regina. (See story below.)

After testifying Thursday afternoon about her work experience in RCMP forensic labs and producing a list of credentials, Fisher was accepted by Justice Leigh Gower as an expert in the field of DNA analysis.

She explained to the jury how things work in the biological section of the Halifax RCMP lab.

"We have many procedures in place to prevent any contamination of samples,” Fisher said. "We have standard operating procedures which we are required to follow to the letter.”

She said there is a universe of reasons why items wouldn't surrender adequate or reliable DNA samples.

A single human cell, for example, contains six nano grams of DNA, Fisher explained.

She said the lab will use DNA samples containing .25 or one 1/24 of normal amount of DNA in a single cell.

Samples of DNA with less than .25 of a nano gram are automatically ruled out, Fisher said.

She told the jury they see everything at the Halifax lab, from clothing, knives with blood on them, other weapons, drywall ....

There was also a DNA match between Cornell and a crack pipe found in the glove box of the black Chevrolet Blazer recovered by police from the ditch along the Alaska Highway, Fisher said.

Defence lawyer David Tarnow asked Fisher in cross-examination if she remains neutral in her gathering and reporting of evidence, even though she is paid by the RCMP.

The Halifax lab processes the samples and she reports the results, the expert told the jury.

She agreed with Tarnow there is always the possibility of transferring DNA from one item to another, if somebody has contact with an individual and then touches another object.

Tarnow touched the shoulder of Crown prosecutor Keith Parkkari, then picked up a pen and asked if it would be possible they would find Parkkari's DNA on the pen.

It would be possible, she said.

Tarnow asked if it's possible the DNA on the pen could then be transferred on to other items.

It would be possible, she said, adding the possibility of transfer would likely grow weaker the further down the chain you went.

Fisher said police officers are trained how to handle items seized as evidence. She added she would expect officers would be using gloves and bunny suits – that sort of protection.

But she also told the jury she has no direct knowledge of what happens in the field.

Proper handling, the defence lawyer added, means changing gloves with the handling of every item.

She agreed.

The jury has already heard how RCMP forensic specialist Sgt. Jim Giczi was dispatched to Haines Junction from Whitehorse.

It was Giczi who single-handedly captured Cornell and Johnson after they walked out of the bush near the Pine Lake Campground while he was driving to the Junction. Other RCMP officers arrived shortly after.

Giczi testified he had his hand on Cornell's back as another officer was placing handcuffs on him. Cornell was co-operative, he said.

The forensic specialist said he was involved in the collection and documentation of items from the investigation through the day for days afterwards, with the assistance of Const. Joshua Penton.

It was Giczi and Penton who were called sometime after the arrest to a site near the campground where the police dog found a rifle under a layer of Moss.

The sergeant explained to the jury how he examined the parking lot of Madley's store, and how he changed his gloves each time he took swabs from items like the safe lying on the ground.

Under cross-examination by the defence lawyer Thursday morning, Giczi acknowledged that testing did not confirm fingerprinting on a number of items at Madley's and on vehicles from the scene.

He noted not being able to get fingerprints "happens all the time.”

Giczi also acknowledged under questioning by Tarnow that a swab he took from Cornell's hand wasn't able to be analyzed for residue from the gun because the wrong type of swab was used.

He was also unable to find any bruising on Cornell's body a few days later that can come from shooting a gun.

The defence lawyer pointed out that there was a period of a couple of days between the vehicles being seized for the investigation and when Giczi continued his investigation work inside the forensic bay at the Whitehorse detachment.

Giczi was also questioned about photos submitted to the trial that were not part of the preliminary hearing last year to determine if there enough evidence to warrant a trial.

Giczi explained that the submissions were made in consultation with the Crown prosecutor.

– With files from Star reporter Stephanie Waddell.