Au pair testifies she flipped on Brendan Banfield because she felt guilty about the killings of his wife and another man

By Lauren del Valle, Dakin Andone, CNN

(CNN) — The au pair who was having an extra-marital affair with Brendan Banfield when he allegedly killed his wife and another man in February 2023 said she finally agreed to cooperate with prosecutors a year after her own arrest because she could no longer carry the guilt and shame.

“I withheld the truth for a long time, just to myself, and it was a lot for me to deal with and I just couldn’t deal with this anymore,” Juliana Peres Magalhães said in court Wednesday.

Peres Magalhães first took the stand a day earlier, on the first day of testimony, to describe the killings inside the Banfields’ Herndon, Virginia, home – and the elaborate scheme she said she and the defendant used to lure Joseph Ryan to the scene to frame him for the killing of Christine Banfield.

On Wednesday, she answered questions about her life after the killings, including her time in jail. She’s been held in detention since her arrest in October 2023.

Peres Magalhães, who was initially charged with murder in the case in October 2023, ultimately pleaded guilty to a lesser count of involuntary manslaughter for fatally shooting Ryan in October 2024. She agreed to cooperate with prosecutors against Banfield in exchange for a recommendation she be sentenced to time served, according to the plea agreement.

Banfield has pleaded not guilty to charges of aggravated murder, as well as using a firearm during the commission of a felony. He faces up to life in prison if convicted on the murder charges.

Throughout her testimony, Peres Magalhães said she can’t recall specific details or dates. When Banfield’s defense attorney challenged the au pair’s credibility on cross-examination, she fired back.

“You were holding the truth yourself and no one else knew,” John Carroll, Banfield’s attorney, asked.

“Well, Brendan does,” she said.

World should know ‘what really happened,’ witness says

Earlier Wednesday, a prosecutor asked her why she ultimately decided to plead guilty.

“The thought of being the right thing to do, I guess,” she testified. “The world deserved to know what really happened and I just couldn’t hold it – I just couldn’t keep it to myself, the feeling of shame and guilt and sadness and all those feelings.”

Peres Magalhães said she’s testifying against Banfield also because it opens the possibility of getting less prison time. She also confirmed on cross-examination that she was only ever offered plea deals that required her to testify against him.

Banfield’s defense attorney reviewed a series of letters and messages Peres Magalhães sent from jail since her arrest.

In one letter she wrote to Banfield in December 2023, she told him, “I’m not going to cooperate with them. There’s nothing on you so I don’t know what they are going to use.”

In another letter to Banfield in the spring of 2024, she wrote, “Sometimes I just think to myself like I can’t believe I’m facing life in prison for someone. Things weren’t supposed to be this way, right? But people are stupid including me and make mistakes … Act without thinking … That’s how I did.”

In July, August and September of 2024, Peres Magalhães sent several messages to her family complaining about her lawyer, who she felt wasn’t working efficiently for her.

Around that time, she also wrote to her family and friends about her complicated relationship with Banfield, who she said wanted to move to Brazil with her.

She expressed more stress over her lawyer’s inefficiency in messages with her family in September 2024, after Banfield was arrested and her own trial – then set for November – grew closer.

Peres Magalhães later confessed to helping Banfield with a plot to kill his wife in a recorded interview with investigators on October 25, 2024, two days after she was released from a 10-day hospital stay.

“There is only so much your brain can take before your body starts responding to the stress as well,” she said in court.

When Carroll challenged her motives for turning on Banfield, Peres Magalhães said she held onto the truth until she couldn’t anymore. And her jail messages didn’t reflect her true feelings, she testified, because she knew her correspondence was being monitored.

Peres Magalhães said she didn’t tell her lawyer or Banfield’s mother – who was paying for the attorney – about her feelings because they didn’t know the truth about the killings.

Au pair details the plot to get rid of Christine Banfield

On her first day of testimony, the Brazilian au pair said she started living with the Banfields in October 2021, and in August 2022, she and Brendan Banfield began their affair. Peres Magalhães testified Banfield began hatching his plan to kill his wife not long after.

He expressed a desire to be with Peres Magalhães instead, she testified, and he thought his wife to be a poor mother. He did not want to pay for a divorce, nor share custody of their young daughter, Peres Magalhães said.

Peres Magalhães said she and the defendant used Christine Banfield’s laptop to create a fake email address and an account on a fetish website. Banfield planned to find a man on the site who they could eventually frame for his wife’s murder, the au pair testified.

They specifically sought someone who would be willing to carry out a rape fantasy and they exchanged messages with multiple candidates for the alleged patsy, according to Peres Magalhães’ testimony and messages shown to jurors in court. Eventually, they found Ryan, who Banfield thought would “play the role that he needed a person to play,” Peres Magalhães said – meaning he would be “aggressive and hold her down and come over to the house and bring stuff.”

In her opening statements, prosecutor Jenna Sands said Banfield posed as his wife and gave Ryan specific instructions: “Christine will be asleep in bed. Come straight upstairs. Cut off the clothing. Tie her. Rape her. Simple and fun. That was how it was posed,” Sands said in court.

That morning, the au pair waited with Banfield’s daughter in her car near the family’s home, she said. When she saw Ryan arrive, she first called Christine -– whose phone had been turned off by her husband, Peres Magalhães said – and then called Banfield, ostensibly reporting the presence of a strange man in the home.

Banfield returned from a nearby McDonald’s where he was waiting, Peres Magalhães said. He and the au pair then entered the home through the basement, where they left the Banfields’ young daughter before heading upstairs.

In the bedroom, Christine Banfield yelled out to her husband that the purported intruder had a knife, the au pair testified. Ryan looked up at them, “shocked,” Peres Magalhães said – and then Banfield shot him.

Christine asked Peres Magalhães to call 911, but the au pair said she hung up the call at Brendan Banfield’s direction. She then watched Banfield repeatedly stab his wife, she said, covering her ears so she wouldn’t hear it.

“When I first saw that happening, I ran to the other side of the bed, and I was just crouching down … and covering my ears and covering my eyes,” Peres Magalhães said. “And a few times I looked and I was able to see him stabbing her.”

They then called 911 again. Peres Magalhães said her “friend” had been stabbed, and Banfield told the dispatcher he was a federal agent who had shot the man who stabbed his wife.

Banfield’s defense attorney refuted the prosecution’s theory in his opening statement, saying investigators initially concluded Christine Banfield had control over her devices – an effort to rebut the theory that Ryan had been “catfished.”

Carroll also accused law enforcement of manipulating evidence to pin the blame on his client, and said Peres Magalhães had been arrested to flip on Banfield.

This is a developing story and will be updated.

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