WINNIPEG -- A woman accused of concealing the remains of six infants in a storage locker had a long-term, extra-marital affair that led to a pregnancy, a former friend testified Tuesday.

Lyn Burdett told Andrea Giesbrecht's trial the 42-year-old was seeing a boyfriend for a few years about a decade ago and, on one occasion, used Burdett as cover when she wanted to spend the weekend with him.

"She told her husband she was going to Mahnomen (Minnesota) with me but she was actually going to (the boyfriend's) house," Burdett told court.

Asked under cross-examination whether she felt bad about helping Giesbrecht go off with her boyfriend, Burdett said no because Giesbrecht "said so many bad things about her husband."

Tuesday's testimony was the first mention of substantial marital strife between Giesbrecht and her husband, Jeremy.

Giesbrecht's husband, who verbally clashed with the two Crown attorneys during a break in the case this week, is scheduled to testify Wednesday. The Crown said it may invoke a section of law governing adverse witnesses when he appears.

Giesbrecht was arrested in October 2014 after the remains were found in plastic pails, bins and other containers in a Winnipeg U-Haul storage locker she had rented. The judge-only trial has already heard it is unclear how long the remains had been there, but some were very decayed.

Medical experts have testified that the infants were at or near full term and were likely to have been born alive. DNA evidence suggests the remains are linked to Giesbrecht's husband and a sample taken from a soiled sanitary napkin inside the Giesbrecht home.

Burdett said Giesbrecht told her around 2006 that she became pregnant from her boyfriend. A few months later, Giesbrecht was no longer pregnant.

"She told me that she lost it," Burdett told the judge.

The trial has also heard that Giesbrecht had 10 legal abortions between 1994 and 2011.

Burdett, who first met Giesbrecht at a casino in 2000, joined a list of other witnesses who said Giesbrecht appeared to hide at least some of her pregnancies.

In 2009, Giesbrecht appeared to again be pregnant -- "probably about six months," Burdett said.

"She just said she was gaining weight. I thought she was pregnant though."

Under cross-examination, Burdett admitted she has no proof Giesbrecht was pregnant, but she was adamant that it was the only plausible explanation for the weight gain.

Another witness told court Giesbrecht concealed her pregnancy with her first son until after he was born in 1997.

"I was very surprised. I didn't know she was pregnant," said Heather MacQuarrie, who had been friends with Giesbrecht since 1990 and was a maid of honour at her wedding in 1999.

Burdett and some previous witnesses have testified Giesbrecht would wear loose-fitting baggy clothes that would conceal any weight gain.

Burdett testified that when Giesbrecht appeared to be pregnant in 2009, she wouldn't take her jacket off inside the casino. A few months later, "she'd be back in her T-shirt and jeans" and appeared skinny again, Burdett said.