Ana Walshe’s lover, William Fastow, took the witness stand on Thursday during the murder trial of her husband, Brian Walshe. Fastow revealed that their “intimate” relationship began before her mysterious disappearance on January 1, 2023.

Fastow, who works as a realtor, had assisted Ana in securing a place to live in Washington, D.C., where she traveled for work while still residing with her family in Boston.

In his testimony, Fastow mentioned that he, too, had children and was living separately from his wife at the time.

William Fastow was seen leaving an open house in Washington, D.C.’s Spring Valley neighborhood on Saturday, November 29, 2025. During the trial, he admitted to having an affair with Ana Walshe, a fellow realtor. (Fox News Digital)

Fastow recounted how their connection deepened as they discovered shared interests in fitness and the challenges of parenting, leading eventually to their romantic involvement.

Although he never stayed at her Washington townhouse overnight, she stayed at his, he said. He said he did not keep the affair a secret generally, but that Ana had told him that if her husband ever found out, she wanted him to find out from her.

Still, the two went on a trip to Dublin, Ireland, for Thanksgiving in the months before her murder. After Dublin, Ana flew to Serbia to visit her mother, while he returned to Washington. They also spent Christmas Eve together in Washington, he said, allegedly infuriating her husband when her flight was delayed. She drove from Washington to Cohasset.

She had also set up rooms for her three children in her townhouse, he said, anticipating that they would be moving in there.  

William Fastow arrives at Norfolk Superior Court in Dedham, MA, Thursday, Dec. 4, 2025. Fastow was reportedly the boyfriend of Ana Walshe, and was testifying in the murder case against her husband, Brian Walshe. (David McGlynn for Fox News Digital)

“Ana was extremely disappointed that she wasn’t in a position to be the mother she believed the children deserved,” Fastow testified.

Ana Walshe wears a Washington Capitals jersey in a December 2022 post. (Ana Walshe/Instagram)

He testified that Ana told him that her children lived with their father in Cohasset, a suburb of Boston, because Walshe’s home confinement for a federal art fraud conviction was contingent on him being their primary caretaker.

Prosecutors have alleged two potential motives in the slaying. The first is anger over the affair. The second is because he allegedly believed he would have a better chance of avoiding federal prison if his wife were out of the picture, and he was the only caretaker for their three children.

Brian Walshe arrives at Norfolk Superior Court in Dedham, Massachusetts, Monday, December 1, 2025. Walshe is facing murder charges for the death of his wife, Ana Walshe. (David McGlynn for Fox News Digital)

Walshe’s defense has denied that he had any knowledge of the affair, although he mentioned Fastow more than once during interviews with detectives before his arrest and allegedly looked him up on the internet before Ana’s disappearance.

Murder suspect Brian Walshe listens during his final pretrial hearing on Monday, Nov. 17, 2025. He is accused of killing and dismembering his wife, Ana Walshe, whose remains have not been found.  (Pool)

During cross-examination, Walshe’s defense attorney repeatedly referred to Ana as “Mrs. Walshe” to underscore how Fastow was carrying on an affair with a married mother of three. 

Her remains have not been found, but prosecutors showed the jury Wednesday a saw and hatchet recovered from a dumpster near Walshe’s mother’s house that the defendant allegedly used to dismember his wife. The same dumpster also had her COVID-19 vaccination card, clothes, bloody towels and a cut-up rug suspiciously similar to one taken from the family home.

Janet Cotter, a woman who ran into Ana at a nail salon on Dec. 31, 2022, testified that Ana was friendly and warm and was excited to attend a New Year’s Day dinner with her husband in the north shore town of Marblehead. Once she realized Ana was missing, she said, she called Cohasset police and alerted them to their conversation. 

The general manager of the Clairmount apartment complex, where Walshe’s mother lived and where prosecutors say police found bags of tools and Ana’s clothing, took the stand and confirmed she provided police with surveillance footage from the property. 

She testified the property has four outside cameras, three of which focus on the back of the building where two gated areas contain the building’s dumpsters.

Prosecutors played some of the video, which had several time skips but showed a man alleged to be Walshe getting out of a Volvo like the one he drove and throwing heavy bags into the dumpster.