Accused killer Kalen Schlatter started testifying in his own defence Monday at his first-degree murder trial in the death of Toronto woman Tess Richey, and told the jury that she was alive the last time he saw her.

"Mr. Schlatter, did you murder Tess Richey?" defence lawyer Lydia Riva asked her client in Superior Court in Toronto. "Absolutely not," he responded.

"Did you sexually assault her?" she then asked. "Absolutely not," he said.

For over five weeks, the jury has heard witness testimony about the 23-year-old Toronto man, who the Crown alleges sexually assaulted and then strangled Richey, before leaving her body at the bottom of an outdoor stairwell in the city's gay village in 2017.

Schlatter has pleaded not guilty in connection with the 22-year-old's death. His cross-examination by the Crown is slated for Tuesday morning.

Schlatter began his testimony by telling the jury that on the evening of Nov. 24, he drank with a couple of friends before heading to Crews and Tangos, a well known drag bar in the city's gay village.

After last call, he ended up talking with Richey and her friend Ryley Simard outside the club, he said.

"They seemed like nice people, nice sociable people," Schlatter said. Richey, he told the jury, spent considerable time talking about how her ex-boyfriend had cheated on her. The two had just broken up, court has heard.

Tess Richey, 22, went missing on Nov. 25, 2017 after a night out with a high school friend. Her body was found the day before what would have been her 23rd birthday. (Tess Richey/Facebook)

After getting hot dogs and wandering around the area in the early morning hours of Nov. 25, Simard told Richey she wanted to leave. Richey wanted her friend to stay, and so the two got into an argument, Schlatter testified.

The two friends then walked away from each other, he said.

"Tess seemed a bit more upset from the argument, so I walked over to her to check if she was alright," he said, adding that Richey then asked him to sit and talk with her at a bench on Church Street.

'She asked me to go with her'

Schlatter said that a little while later, Richey asked if it was OK if she kissed him.

"We stand up and give each other a hug and kiss," he said. "We hold hands and she asked me to go with her."

He told the court that Richey then asked him to follow her up a driveway at 582 Church St., towards an outdoor stairwell in a construction site.

The jury has previously seen security camera footage of Schlatter and Richey together in that area — including video showing the pair walking up the driveway before Schlatter emerges alone about 45 minutes later, heading back the way they came.

The officer who examined the video told the court he watched for at least two hours after that and did not see anyone else going to or coming from the area.

WATCH: Security footage shows Schlatter and Richey in alley before he leaves alone

This footage of Kalen Schlatter and Tess Richey was played at Schlatter's first-degree murder trial. The two can be seen walking together down an alleyway. Schlatter leaves on his own some time later. 0:24

Court has also heard Schlatter's semen was found on Richey's pants and his saliva was on the inside of her bra.

Schlatter testified Monday that he and Richey went down the stairs and started making out. He said he told Richey that he had some condoms, but she said she was on her period, so they couldn't have sex.

The two continued to make out, and Schlatter "came in his pants," which he called "embarrassing."

Schlatter said he then asked Richey if she wanted to come back to his family's home, but she declined.

He testified Richey then pulled out her phone and told him he could leave, so he left her at the bottom of the stairs.

Schlatter said he felt bad for leaving her there. "I should have stayed with her," he said.

At this, members of Richey's family visibly recoiled in the courtroom.

Schlatter appears to cry for the 2nd time in court

At one point during Monday's testimony, while describing how a detective told him that Richey died of neck compression, Schlatter appeared to cry while in the witness box. He became red faced, dabbed his eyes with a tissue, and took several moments to compose himself.

This is the second time Schlatter has appeared to cry in court. He acted similarly when photos of Richey's body were shown earlier in the trial.

Court previously heard testimony from an undercover cop who spoke with Schlatter after his arrest, who testified that Schlatter told him he "pretended" to get emotional when detectives showed him photos of Richey's body.

"In reality, it didn't bother him at all," the officer testified Schlatter said.

Kalen Schlatter, left, listens as Rachel Richey, centre, testifies and Crown attorney Beverley Richards looks on. (Pam Davies)

"Did you tell the undercover that you pretended to be emotional?" Riva asked Schlatter Monday.

Schlatter said he told the cop that he "acted emotional" because he actually was upset.

Further jailhouse evidence from the trial came from Schlatter's former cellmate in the Toronto South Detention Centre, who previously testified that Schlatter confessed to strangling Richey with a scarf when she refused to have sex with him hours after they met.

Schlatter said Monday that he never told his cellmate he killed Richey.

His cellmate, who cannot be named because of a publication ban, told the jury that Schlatter cried himself to sleep at night in his cell because he missed his "mommy," but had "no remorse" about Richey's death.

"Did you sometimes cry at night?" Riva asked.

"Yes," Schlatter said. "I missed my family ... I felt bad for Tess, and I felt bad that I was in jail for something I didn't do."

CBC Toronto's Adam Carter reported live from inside the courtroom Monday. Here's a recap of what Schlatter said in the witness box:

adam.carter@cbc.ca