FAIRFAX, Va. — A Brazilian au pair who fell in love with an IRS agent pleaded guilty to involuntary manslaughter Tuesday in what prosecutors say was an elaborate double-murder plot to frame another man for stabbing his wife.

For months after the murders of February 24, 2023, it might have seemed that Juliana Peres Magalhães and IRS Agent Brendan Banfieldgot away with it, according to new details prosecutors revealed in court to support his guilty plea.

Christine Banfield, a pediatric intensive care nurse with a 4-year-old daughter, had been fatally stabbed in the neck, and Brendan Banfield, her husband, and their babysitter had shot her apparent killer: a man. that she had been lured to the bedroom with promises of rough sex.

Magalhães had called 911 at the Herndon, Virginia, home and was hyperventilating at the scene as he described the murders.

The detectives didn’t believe it, but it took time to build their case. Meanwhile, the au pair who lived there moved into the master bedroom with Banfield and posted photos of them as a couple, authorities said. When she was arrested in October 2023, there was a photo of her with Brendan Banfield on the nightstand.

And then, as he remained in prison for more than a year, he refused to say anything more.

A long-awaited forensic report on evidence of blood spatter Then it went in and prosecutors said it showed that Brendan Banfield had smeared blood from Christine Banfield’s wounds on the body of Joe Ryan, the man they had tried to frame for stabbing her. Authorities arrested Brendan Banfield in September on charges of aggravated murder.

Banfield’s attorney, John F. Carroll, said in court before he was denied bail in September that the evidence “just doesn’t add up” to him killing his wife.

In October, Magalhães agreed to cooperate with police in his second interview since the day of the crime. Days later, on Tuesday, two weeks before he was scheduled to go to trial on second-degree murder and felony firearm charges, Magalhães pleaded guilty to Ryan’s murder and said he had agreed to help in the husband’s ruse to kill his wife and make it look like they both shot a predator.

“Are you pleading guilty because you are actually guilty of this crime?” Chief Judge Penney Azcarate questioned Magalhães before accepting his guilty plea to a single count of involuntary manslaughter, reduced from murder and firearm offense.

“Yes,” she replied quietly.

The sentencing of Magalhães, raised on the outskirts of Sao Paulo, now awaits the conclusion of the trial against Brendan Banfield. Depending on her cooperation with authorities, attorneys said in court they could agree to have her sentenced for the time she has already served.

“Much of the information that led to this agreement cannot be made public at this time, due to the upcoming criminal trial against the other defendant in this matter,” said Fairfax County Prosecutor Steve Descano.

Laying out facts that Magalhães corroborated in court, prosecutors said she made several calls to 911 that day. The first lasted a few seconds, no words, just the sound of someone’s guttural moan in the background. Then, about 15 minutes later, another call came in, saying that an intruder had stabbed her friend. Brendan Banfield then picked up the phone and said he had shot a man who was stabbing his wife.

An officer’s body camera footage presented in court last month shows Magalhães kneeling in the driveway, apparently bewildered and unable to catch her breath.

“There was a lot of blood,” Magalhães said while hyperventilating. “Brendan said, ‘Please put the knife down, put the knife down,’ because he had a knife.”

He later told detectives that he had shot the intruder in the chest after Brendan Banfield shot him in the head.

But in court Tuesday, prosecutors alleged that she had been lying as part of a ruse to lure another person to the house to be framed in his wife’s murder.

Affidavits say Magalhães began working for the Banfields in late 2021. Assistant Commonwealth’s Attorney Eric Clingan said in court that the au pair and husband began having an affair in August 2022. Shortly after , Brendan Banfield began plotting to kill his wife, Clingan said. .

To cover up the deception, Clingan alleged that Brendan Banfield created a profile for his wife on a social media platform for people interested in sexual fetishes and paired her with Ryan. Soon they were chatting via Telegram, an encrypted messaging app, and Magalhães was posing as Christine Banfield on a voice call. Ryan agreed to go to the house for what appeared to be a consensual sexual encounter.

“At several times before the 24th, Peres Magalhães expressed to Brendan Banfield that he did not believe he would follow through with this plan and, at other times, he told him that he did not want to continue,” Clingan said. “But he insisted it was too late for her to back out.”

Clingan said Magalhães and Brendan Banfield left the girl in the basement and then followed Ryan to the bedroom, guns drawn.

Authorities monitored his phone conversations at the Fairfax County Jail. In a call last month, Clingan said Brendan Banfield’s mother, who paid for the au pair’s legal defense, talked about the consequences ‘snitches’ would face in jail.

In another, between Brendan Banfield and the au pair, Magalhães said: “I hope you don’t stay with me just because you’re afraid I’ll turn against you.”