A photograph of what appears to be bones burning inside an animal incinerator was the focus of testimony Tuesday in the trial of two men accused of killing a young Toronto woman whose body has not been found.

Scott Rufolo, an archeologist with the Canadian Museum of Nature, testified on behalf of the defence that he believes the objects in the photo found on Dellen Millard's phone are animal bones.

Under cross-examination from Crown lawyer Jill Cameron, however, Rufolo waffled.

"It's possible it could be a human radius," he said, describing one of the forearm bones.

The Crown contends Millard, 32, of Toronto, and Mark Smich, 30, of Oakville, Ont., killed 23-year-old Laura Babcock in July 2012 because she became the odd woman out in a love triangle with Millard and his girlfriend.

They allege the pair burned Babcock in an animal incinerator, named The Eliminator, at Millard's aircraft hangar near Waterloo, Ont.

Both men have pleaded not guilty to first-degree murder.

Rufolo told court earlier on Tuesday that he believed the photo shows an upper arm bone and shin bone of a deer or goat.

"It should also be stated that I'm offering an opinion based on a poor quality image that is based on patterns of shadow and light," he said under questioning from Millard, who's representing himself.

"What I see there is my opinion with what you'd expect with a deer or other animal of related size and doesn't match easily with human bones, if I have accurately judged the photograph."

The jury has seen the photo, taken on July 23, 2012, on several occasions.

Millard had Rufolo zoom in close on the photo and go over what he could see in painstaking detail. Babcock's mother, Linda, winced, closed her eyes and shook her head often throughout the testimony.

Court heard this was Rufolo's first time giving an expert opinion in court and he did not realize he was going to testify until recently. He said his report was rather casual, did not include precise measurements and he did not bring his notes because of the last-minute notice he was given.

He wrote down his notes on a hotel notepad Monday night, he said.

Millard tried to recover on re-examination, but was cautioned by the judge.

"You're repeating your questions, now stop it. That's an order," Justice Michael Code said.

"Your honour I apologize, this is my first time doing this," Millard said.

Tracy Rogers, a forensic anthropologist who is an expert in identifying human remains and the effects of burning on human bones, has previously testified the objects in the image appear to be bones from a human arm.

"Based on the shape comparison, one is similar overall to the human humerus, the upper arm bone," Rogers said. "One looks similar in overall shape and size to a human radius, the end close to the wrist."

Rogers also could not be certain because she said she was only able to analyse a poor quality photograph.

Late in the day Millard called Gabe Austerweil, whose son dated Babcock for a couple of months in early 2012.

Austerweil testified saw Babcock in October 2012, months after she was reported missing by her friends and family. He knew she was missing, but told court he didn't tell her family or police until a detective interviewed him in May 2013.

He said he saw her at a nut store in Toronto asking about hemp for her diet.

"People have said I'm crazy, but I saw what I saw," he said.

Under cross examination from the Crown, Austerweil read through his police statement where he told a detective he saw her in March 2013. He said he saw her in October 2012.

He said he was good at recognizing faces.

The Crown showed him a photograph of Babcock that police released when she went missing.

"Would it surprise you to know that's a picture of her?" Cameron asked.

"Yes," he said.