The defence team for alleged killer Kalen Schlatter accused another man of killing Toronto woman Tess Richey in court Thursday, as Schlatter's first-degree murder trial nears its conclusion.

The witness, who can only be referred to as J.G. because of a publication ban, fielded questions from defence lawyer Lydia Riva through most of the day.

"You assaulted her, and there was a struggle, and you killed her, right?" Riva said.

"No ma'am," the witness responded.

Under cross-examination from the Crown, J.G. told the jury he has autism spectrum disorder and Asperger's syndrome. He spoke very softly, mumbled, and often fidgeted with something in his hands in the witness box.

The witness said he is five-foot-three-inches tall, though he appeared to be shorter than that. Over the course of his testimony, Riva showed the jury a photo that showed his bare arms, which are muscular.

'Looking for sex'

Riva alleged that on the morning Richey vanished, the witness was "out in [his] neighbourhood ... looking for sex."

At first, J.G. responded very softly, and said he wasn't. But he later changed his answer after Riva showed him a portion of a prior statement he gave police, in which he said he was looking for sex, "or something."

Riva pressed him on why he changed his answer. "Is it because you don't want us to know you left your apartment with the objective of finding sex?" Riva asked.

"Yes ma'am," he responded.

During cross-examination from assistant Crown attorney Jennifer Stanton, the witness said he did not have sex with anyone that morning. J.G. also said it can sometimes be tough for people to understand the way he speaks.

Schlatter's DNA found on Richey's clothing

The Crown alleges Schlatter 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, 23, has pleaded not guilty in connection with the 22-year-old woman's death.

Kalen Schlatter, who is charged with first-degree murder in the death of Tess Richey, is seen here being placed in a cell after his arrest. (Court exhibit)

Court has heard Schlatter's semen was found on Richey's pants and his saliva was on the inside of her bra. No physical evidence related to the defence's alternate suspect has been presented at the trial.

The jury has also seen security camera footage of Schlatter and Richey together early that morning.

That includes video showing the pair walking up a driveway to the outdoor stairwell where her body was later discovered at 582 Church St., before Schlatter emerges alone about 45 minutes later, heading back the way they came.

Court heard J.G. was also out in that area in the early morning hours of Nov. 25, and ran into Richey alongside two other people — Schlatter, and Richey's friend, Ryley Simard.

The witness said Richey repeatedly tried to say hello to him.

"Why did you think she wanted to get your attention?" Riva asked.

"I don't know ... maybe she was just interested in talking to me," he said. J.G. also told the jury that the people Richey was with repeatedly discouraged her from talking with him, saying things like, "Don't go with him, don't talk to him."

Richey's family distributed this poster in an effort to find her. (Court exhibit)

During cross-examination, J.G. said he lived alone back in 2017, and did not have many close friends.

"You struggled quite a bit even talking to other people?" Stanton asked.

"Yes ma'am," he responded.

Stanton also suggested that Richey calling out to him was a "significant thing" for him, because he doesn't get much attention from women. "For some people that might not be such a big deal, but for you it meant something?" she asked.

"Yes," he responded.

Trial nearing its conclusion

In court's afternoon session, Riva showed several videos of the witness repeatedly wandering around areas where Schlatter, Richey and Simard were situated that morning.

Riva suggested he was following them, but the witness kept saying he was "seeing who was out and about." During cross-examination, he said he "quite often" went on walks and jogs around the area at that time.

Stanton asked J.G. if approaching Richey is something he would do.

"Talking to girls is still difficult," he said.

She also asked what he did specifically the second time Richey tried to speak with him, before Schlatter told her not to.

"I believe I just shyly smiled at her," he said.

It's expected the evidence portion of the trial will wrap up on Friday.

CBC Toronto reporter Adam Carter reported live from inside the courtroom Thursday. Here's a recap:

adam.carter@cbc.ca