Bonnie McLachlan is on trial in Prince Albert, accused of sexual exploitation of a student. Her husband, James McLachlan, holding her hand, testified she was never unfaithful. (Ryan Pilon/CBC)

A former teacher accused of sexual exploitation over an alleged relationship with a Grade 9 student some 20 years ago has testified she was never alone with the youth, who was 15 at the time.

Bonnie McLachlan, 53, is being tried in Prince Albert, Sask., before a judge and jury.

During testimony Wednesday, McLachlan said there was no sexual relationship with her accuser during the 1993-94 school year.

Earlier in the trial, the alleged victim told the jury that a sexual relationship had developed and that McLachlan had initiated it.

He said their first encounter was in the teacher's car, after the youth had been working out at a local gym.

Witnesses for the prosecution said the two appeared to be an item. One said he saw the pair holding hands in a car on a field trip to Banff. And, in Red Deer, a witness testified the two were seen on a bed under the covers, although the room had other students in it at the time.

'She's never been unfaithful to me.' —James McLachlan, husband of accused teacher

Another witness claimed that, while in Banff, the pair were kissing and behaving in a seductive manner in a pool. That witness also claimed to have overheard explicit sexual talk in a phone conversation between the two.

McLachlan told the court the two were never alone during the Banff trip.

She also testified that there were no problems in her marriage, a claim supported by her husband who also testified as a defence witness.

"She's never been unfaithful to me," James McLachlan told the jury. He also denied suggestions that he put a tape recorder in her car to see if she had been cheating.

The jury also heard from school officials from the time of the alleged relationship.

A former vice-principal testified that he was aware of allegations about a relationship between the two, but nothing of a sexual nature.

The former principal said much the same, that there were allegations about a relationship but the principal could not recall any concerns that the relationship had involved sex.

The trial adjourned for the day Wednesday afternoon. It was set to resume Thursday with one more witness scheduled to testify.

With files from CBC's Ryan Pilon