(CNN) — Brian Walshe on Thursday came face-to-face for the first time with the man who had been having an affair with his wife before her death, as he took the stand to testify in Walshe’s murder trial.

Washington, DC, real estate broker William Fastow is a key witness for the prosecution, as his testimony could offer jurors a potential motive while they weigh whether Walshe killed his wife, Ana Walshe, around New Year’s Day in 2023.

The jury also saw surveillance footage and GPS data from Brian Walshe’s phones that prosecutors are using to bolster their case that Walshe bought supplies to dismember his wife and then dispose of her body and belongings after her death.

Walshe maintains he did not kill the corporate real estate manager and mother of three – though he has pleaded guilty to illegally disposing of her body and misleading police, unbeknownst to the jury. He faces life in prison without the possibility of parole if convicted of her murder.

Here are the takeaways from the fourth day of witness testimony.

Stressors weighed on the Walshes’ marriage before she vanished, Fastow said

Fastow testified Thursday that he started an intimate relationship with Ana Walshe within weeks of her relocating to the city where he sold her a townhome in the spring of 2022.

Ana Walshe had relocated to DC for work. She told Fastow her children were living with their father in Massachusetts because her husband was subject to home confinement due to a pending federal case in which he pleaded guilty to charges related to selling forged Andy Warhol artwork.

That confinement was predicated on Brian Walshe being the primary caregiver for their children, Ana Walshe told Fastow, according to his testimony.

Still, Ana was “despondent” over the fact that she felt she wasn’t in a position to be the mother her children deserved, Fastow testified.