"Rider isn't here."

That was the reason for cancellation Uber driver Marlon Allamby selected on his app on Nov. 25, 2017 when Tess Richey didn't show up for her Uber Pool ride.

Allamby didn't think anything of it at the time. Sometimes riders just don't get to their pickup point, he testified in court Monday morning.

But the Crown at the trial of the man who faces a first-degree murder charge in Richey's death alleges she didn't show up because Kalen Schlatter led the 22-year-old to an outdoor stairwell before sexually assaulting and strangling her.

Richey was reported missing in November 2017 after a night out in the Church and Wellesley area. Schlatter, 23, has pleaded not guilty to first-degree murder.

In her opening address to the jury, Assistant Crown Attorney Bev Richards said Schlatter's DNA was found on Richey's pants and bra.

She also said surveillance video shows Schlatter leading Richey to a stairwell of a building under construction around 4:14 a.m. on Nov. 25 — around the same time she was supposed to get into Allamby's Uber.

Richards said the video, which is expected to be presented at trial, will then show Schlatter leaving the area alone 45 minutes later.

Kalen Schlatter has pleaded not guilty to first-degree murder. (Facebook)

For much of the day Monday, the jury heard from witnesses who were in the area the day Richey's body was found. One of those was William Ayers, who runs a business called Zendog at 584 Church St., which is next door to the site where Richey's body was discovered on Nov. 29.

"We heard screaming outside," Ayers testified. "There was a woman who said there was a body in the alleyway."

That matches up with Friday's testimony from Ann Brazeau, who found Richey's body in an outdoor stairwell.

"I just saw her lying there and I went into complete shock. Horror. Disbelief. I couldn't process or make sense of what I was seeing," Brazeau said. "I was terrified."

Const. Rob Chevalier also testified Monday, and told the jury about his work as a Toronto police officer in the Church and Wellesley area.

He said he spoke with Brazeau and Richey's mother, Christine Hermeston, not long before they found the body.

"Christine didn't look well," he said, adding that it seemed like she wasn't sleeping or eating at the time.

Chevalier testified he was investigating a nearby area when he heard a scream that afternoon. Not long after, a call came in over the radio for a found body.

He rushed to the area where the call came in, and found Brazeau and Hermeston visibly upset out in front of 582 Church St.

Chevalier then went up the driveway and peered down the stairwell himself — and recognized Richey's body from a wanted poster he had seen.

"She didn't look like she was alive at that point," he said.

adam.carter@cbc.ca