A jury has found Christopher McDonald guilty of first-degree murder and aggravated sexual assault in the 2008 death of Corinne Burns.
The eight men and four women began deliberating Wednesday afternoon after instructions from the judge, including the fact that most of the evidence is circumstantial.
It took them five hours to reach a verdict.
Family members of Burns burst into tears when it was read aloud in court.
Burns, 29, was found lying in Guelph's Norm Jary Park, face up, naked and spread eagle in May 27, 2008.
McDonald was arrested in 2010, two years later. At that time he was already behind bars after pleading guilty to aggravated assault in connection with an incident in Barrie.
In that case, McDonald was found with a prostitute who had been beaten.
However, he had maintained his innocence in the Guelph murder, and his attorney argues that Burns died as a result of a drug overdose.
McDonald's defence lawyer Angela McLeod says she will encourage her client to appeal, saying the Barrie assault should not have been allowed as evidence.
The jury came to their verdict after reviewing 65 pieces of evidence and the testimony of 28 witnesses over the course of the trial.
McDonald will be sentenced on Friday. Family members of Burns will read victim impact statements at that time.
