TORONTO -- The judge at the trial of two men accused of killing a young Toronto woman five years ago and then burning her body is instructing the jury on how to deal with circumstantial evidence.

Justice Michael Code began his 300-page charge to the jury this morning in the first-degree murder trial of Dellen Millard and Mark Smich in the presumed death of 23-year-old Laura Babcock, whose body has not been found.

The judge says the case hinges upon a "large and complex" body of circumstantial evidence about two main issues: whether Babcock is dead and whether Millard and Smich caused her death from an unlawful act.

The prosecution alleges Babcock was killed in the summer of 2012 after becoming the odd woman out in a love triangle with Millard and his girlfriend, Christina Noudga.

Millard, 32, of Toronto and Smich, 30, of Oakville, Ont., have pleaded not guilty and both have said the Crown has not proved that Babcock is dead.

The judge told the jury his instruction will last multiple days before they can begin deliberating.

"Facts may be proved by circumstantial evidence," Code said.

"It is all about inference drawing. You observe some fact and from that fact you draw an inference or conclusion."

The judge hammered home the point multiple times Thursday that circumstantial evidence must be looked in totality, not each piece of evidence in isolation.

He summarized seven key points of circumstantial evidence that came up throughout the seven-week trial: motive, opportunity, evidence of the incinerator and Millard's handgun purchase, Babcock's disappearance, her risky lifestyle, the use of the incinerator on July 23, 2012, and statements made by Millard and Smich after the Toronto woman disappeared.

In its closing address on Wednesday, the Crown said a "mountain" of circumstantial evidence points to Millard and Smich killing Babcock at Millard's home some time after 8 p.m. on July 3, 2012 and then disposing of her body at Millard's farm near Waterloo, Ont.

Smich's lawyer told the jury on Wednesday that his client had no motive to kill Babcock because he was never part of a love triangle and all the Crown has is a rap song in which Smich says he killed a girl and burned her body.

Millard, who is representing himself, told the jury in his closing address earlier this week that several witnesses testified to having seen or heard from Babcock after July 4, 2012.