In December 2016, an undercover detective, a tall man with shaved head and commanding presence, launched an undercover operation, posing as "Shannon," the mother of an 11-year-old girl.

The target of the operation, Wesley Vander Leeuw, is now on trial in an Edmonton courtroom on five child pornography charges, including three counts of making arrangements to commit sexual offences against a child.

The detective, who can be identified only by initials S.H., was acting on a tip from a woman who had responded to a Craigslist ad posted in April 2015 by a man who said he was looking for "some fun" with a female or couple.

Vander Leeuw, who had once been involved in coaching youth soccer in Edmonton, admits he posted the ad. In it, he described himself as a, "good-looking, clean, ... fun, open-minded guy."

Craigslist ad posted by the accused online. (Court exhibit )

Text messages between Vander Leeuw and the woman were entered as exhibits at the trial. She told police she became alarmed when the man who identified himself as Wes introduced the idea of including children in sexual activity.

He asked, "Are you okay with having a child while in a polyamorous relationship?"

Vander Leeuw wanted to know if her daughter was in Grade 2 or 3, asking, "When are you okay with her having sex?"

Text messages sent by the accused to a woman he met through craigslist. (Court Exhibit )

More than a year and a half later, the undercover officer texted Wes, posing as the woman who had tipped off police, claiming to have a new phone number.

The text conversation quickly turned to sex, once he found out "Shannon" had an 11-year-old daughter.

"How do you want your daughter to learn about sex?" Wes asked.

Eleven minutes later he wrote, "Would you like to find someone you can trust to teach your daughter?"

On the witness stand, the detective described the text messages as "very alarming."

"It was very concerning to me," S.H. testified. "This is condoning of sex acts for underage children."

Text messages sent by the accused to an undercover police officer (Court exhibit )

Vander Leeuw began to propose the idea of a meeting.

"Would you want to watch or be in the house or out of the house?" he asked.

When the undercover officer posing as "Shannon" asked if there was anything that was taboo or off-limits, the accused responded.

"Taboo is what we decide," Vander Leeuw wrote. "She has the right to learn from someone who is safe and knows what they are doing."

In a later exchange, the accused graphically proposed specific sexual acts he wanted to perform on "Shannon" and her daughter.

"That is a description of a sex act with a child who is under the age of consent," the undercover officer testified. "That qualifies as written child pornography."

S.H. said he gave the accused numerous opportunities to change his mind or back away from his requests.

The officer stopped communicating with Vander Leeuw for a week in January 2017. S.H. said the accused unsuccessfully tried to reach him more than a dozen times.

The officer felt like he'd given the accused more than enough chances to back out, so he decided to proceed with the meeting and arrest.

According to an agreed statement of facts entered as an exhibit at the trial, Vander Leeuw was arrested at a west Edmonton Starbucks on Jan. 25, 2017.

Under cross-examination, S.H. admitted some of the text messages sent by the accused are "open to interpretation" or multiple interpretations.

The trial is expected to conclude on Thursday.