DNA from the man accused of raping a woman in a downtown Calgary parkade was found inside the victim, jurors heard as Andy Ntunaguza's sexual assault trial got underway on Tuesday.

Prosecutor Deven Singhal told the jury — made up of 10 men and two women — that the victim, a woman in her 40s, has been homeless for much of her life and suffers from lupus.

When security guards and police found her in the fifth floor stairwell in December 2015, both her eyes were swollen shut and she had cuts and scrapes covering her body. The woman — whose identity is protected by a publication ban — was naked from waist down and bleeding from her face.

The badly beaten woman was taken to hospital suffering serious injuries after what Singhal called a "savage sexual attack."

Ntunaguza is charged with aggravated sexual assault, forcible confinement, and overcome resistance by choking.

"When she called for help, when she cried, she was constrained, choked, held by the neck," said Singhal.

The attack happened around 3:30 a.m. on Dec. 20, 2015.

Around the same time security guards found the victim, video from the parkade shows a man the Crown says is Ntunaguza leaving the building.

The prosecution says this image shows Andy Ntunaguza leaving the downtown parkade around the same time the victim was found by a security guard. (Calgary Police Service)

When police responded to the scene, the woman told them she had been dragged into the stairwell by her hair and raped.

When asked about the victim's demeanour, one of the first officers on scene said she was "very shaken up."

"Her hands were covering her face as if to protect herself from somebody else harming her," said Const. Maja Vadak.

Ntunaguza's lawyer, Dale Fedorchuk, has not yet indicated what his defence will be.

Court of Queen's Bench Justice Adam Germain is presiding over the two-week trial.