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Brendan Banfield has been accused of murdering his wife and a stranger(Image: Fairfax County Police Department)

A husband and dad-of-one has been accused of murdering his wife and a stranger at his home a year after striking up an affair with his family’s au pair.

Brendan Banfield, 39, has been charged with the aggravated murder following the killings of his wife, Christine Banfield, 37, and Joseph Ryan, 38, at his home in northern Virginia, the US. Banfield was involved in a relationship with his and Mrs Banfield’s 25-year-old au pair Juliana Peres Magalhaes, from Brazil, when the two were killed by stabbing and gunshot wounds respectively.

Prosecutors have accused Banfield and Magalhaes of forging an elaborate double-murder scheme in a bid to frame another man for his wife’s stabbing.

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Banfield was having an affair with Juliana Peres Magalhaes at the time of the killings(Image: Fairfax County Police Department)

The two were with the wife and Ryan on the morning the victims were killed in the primary bedroom of the Banfield home, court records say. Authorities have said on that day, Banfield and Magalhaes told officials they saw Ryan, a stranger, stabbing the wife after he entered the house. Then they each shot the intruder, Banfield and Magalhaes said at the time.

Prosecutors have painted a different picture, however, arguing that Brendan Banfield and Magalhaes lured Ryan to the house and staged it to look like he and the au pair shot a predator in defence.

Officials have said Banfield and Magalhaes had a romantic affair beginning the year before the killings. Both the au pair and husband were arrested between 2023 and 2024 and initially handed murder charges in the case. In 2024, Magalhaes pleaded guilty to a downgraded manslaughter charge after giving a statement to officials confirming parts of their theory.

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Christine Banfield was stabbed to death in the 2023 attack(Image: )

In that statement, Magalhaes said she and Brendan Banfield created an account in his wife’s name on a social media platform for people interested in sexual fetishes.

There, Ryan connected with the account in Christine Banfield’s name, and the users made plans to meet on the morning of Feb. 24, 2023, for a sexual encounter that would involve a knife, authorities said based on the statement from Magalhaes. Prosecutor Eric Clingan said last year that the au pair’s statement helped the state solidify its theory ahead of trial.

“With 12 different homicide detectives, there were 24 different theories,” Clingan said. “Now, one theory.” Not all officials investigating the case have believed Banfield and Magalhaes catfished Ryan.

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Banfield kept a photo of himself and Magalhaes at his residence in Herndon(Image: AP)

Brendan Miller, a former digital forensic examiner with the Fairfax County Police Department, testified last year that he analyzed dozens of devices and concluded Christine Banfield had connected with Ryan herself through the social networking platform. An evidence analysis team at the University of Alabama peer-reviewed and affirmed Miller’s digital forensic findings, according to evidence submitted to the court.

Miller was transferred out of the department’s digital forensics unit in late 2024, though a former Fairfax County commander testified the reassignment was not punitive or disciplinary.

John Carroll, Banfield’s attorney, argued that Millers’ transfer was directly tethered to the case. He also said in court that Fairfax County police reassigned the case’s lead detective after that man had pushed back on the top brass’ catfishing theory. “It is a theory in search of facts rather than a series of facts supporting a theory,” Carroll said.

Banfield, whose daughter was at the house on the morning of the killings, is also charged with child abuse and felony child cruelty in connection with the case. He will also face those charges, which he denies, during the aggravated murder trial.