Nanny love triangle murders trial pits dueling stories of mastermind behind case ‘out of a TV movie’: expert

WARNING: GRAPHIC CONTENT

The first week of testimony in the Virginia trial of Brendan Banfield centered on an extramarital affair he was having with the family’s nanny, allegedly prompting the ex-IRS agent to kill his wife and a stranger as part of an elaborate scheme.

Banfield is charged with aggravated murder in the February 2023 killings of his wife, Christine Banfield, and Joseph Ryan inside their home in Herndon, Virginia, an affluent suburb of Washington, D.C. Prosecutors allege he orchestrated the killings to cover up his relationship with the family’s au pair, Juliana Peres Magalhães. Banfield has pleaded not guilty.

"They're calling it 'The Au Pair Affair'—it’s like something out of a TV movie. From the defense standpoint, the primary goal is to frame her as the mastermind by attacking her credibility. As the star witness, the jury’s decision rests on whether they believe her," Kelly Hyman, a criminal defense attorney, told Fox News Digital. 

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Magalhães, who admitted her role in the killings under a plea agreement, told jurors she was involved in a sexual relationship with Banfield and said the two plotted to kill Christine and make Ryan’s death appear to be the result of a consensual encounter gone wrong.

She testified that Banfield controlled the planning, created an online profile using his wife’s credentials, and ultimately stabbed Christine after shooting Ryan.

Under her plea deal, Magalhães faces a significantly reduced sentence in exchange for her cooperation.

"It’s a ‘Tale of Two Cities’: the prosecution paints her as a 22-year-old victim, while the defense flips the script to show an instigator acting out of self-preservation," Hyman said. "By attributing key decisions to her and introducing prior inconsistent statements, the defense will aim to create reasonable doubt. If they can show she has an ulterior motive or a personal gain from the plea deal, they can argue the prosecution hasn't proven the elements of the crime beyond a reasonable doubt."

With Magalhães’ testimony now complete, the trial is expected to shift this week to additional forensic evidence and law-enforcement witnesses.

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A key dispute last week involved who controlled the FetLife account used to communicate with Ryan. Prosecutors pointed to digital evidence and Magalhães’ testimony to argue Banfield was the mastermind behind the keyboard.

The defense countered that multiple people had access to devices inside the home and questioned whether the evidence conclusively identifies Banfield as the account’s operator.

Prosecutors also discussed what they described as the "neatness" of the crime scene, focusing on details such as Christine’s eyeglasses, which appeared carefully placed despite the violence of the attack. The commonwealth argued these details support a narrative that the scene was staged to mislead investigators.

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Jurors also heard testimony that, in the months after the killings, Banfield replaced family photographs in the home with images of Magalhães.

"They had gotten new flooring, new bedroom furniture," Fairfax County Sgt. Kenner Fortner, who testified that he entered the home shortly after the killings in February 2023. "Pictures that had once featured Brendan and Christine had been taken down and replaced with Brendan and Juliana together." 

The defense has yet to present its case. The trial is scheduled to resume Tuesday at 10 a.m.