Affluent Virginia husband and nanny charged with murders in mansion love triangle

Virginia police on Tuesday announced a second arrest in connection with a 2023 double-murder case in the idyllic Washington, D.C., suburb of Herndon.

"Early last year, the double homicide of Christine Banfield and Joseph Ryan shook our entire community. Today, I am pleased to announce that due to the hard work of police and prosecutors, the Commonwealth's Attorney's Office has secured an indictment against Brendan Banfield for the murder of his wife, Christine, and the murder of Ryan," Fairfax County Commonwealth's Attorney Steve Descano announced during a Tuesday press conference.

Brendan Banfield, a husband and the father of a then-4-year-old daughter, and his family's then-22-year-old Brazilian au pair, Juliana Peres Magalhaes, are accused of killing Christine — Brendan's wife and Fairfax County NICU employee — and Joseph Ryan, the 38-year-old man who showed up at her home armed with a knife, in Herndon, Virginia, in February 2023.

Ryan's connection to the family or their au pair remains unclear.

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Brendan Banfield of Herndon, Va., faces charges of aggravated murder and use of a firearm in commission of a felony. (Virginia County Police Department)

Brendan Banfield is charged with four counts of aggravated murder and use of a firearm in commission of a felony.

Magalhaes also faces charges of aggravated murder and use of a firearm in commission of a felony.

Brendan Banfield is charged with four counts of aggravated murder and use of a firearm in commission of a felony. (Fairfax County Police Department)

"On Feb. 24, 2023, I stood in the middle of a cul-de-sac street in Fairfax County and described the deaths of two persons inside of a residential home. Now, 570 days later, we know the deaths of Joseph Ryan and Christine Banfield are, in fact, murders," Fairfax County Police Department Chief Kevin Davis said during a Tuesday press conference.

VIRGINIA AU PAIR MURDER: FETISH PLOT, AFFAIR, GUN RANGE TIED TO DOUBLE HOMICIDE AT HOME, PROSECUTORS REVEAL

Juliana Peres Magalhaes was charged nearly eight months after she fatally shot Joseph Ryan – the man who reportedly had just stabbed her affair partner's wife to death. (Fairfax County Police)

When police initially responded to a 911 call from the residence that day, they found Christine with stab wounds to the neck and Ryan with fatal gunshot wounds in the upstairs bedroom of the home. Authorities transported Christine to the hospital, where she was later pronounced dead, Davis said.

Officials recovered a knife and two firearms from the scene.

"We know Brendan Banfield and Juliana Magalhaes were involved in a romantic relationship at the time of the murders."

— Chief Kevin Davis

"I will not describe our victim Joseph Ryan's involvement with anyone in the case at the moment because this investigation continues," Davis said.

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On Feb. 24, 2023, when Magalhaes told police she left the Banfields' home in the 13200 block of Stable Brook Way in Herndon to take their young daughter to the National Zoo. She told authorities that she had begun driving but realized she had forgotten the lunches she packed for their excursion back inside the house, so she turned around and noticed an unfamiliar car in the driveway.

Fairfax police arrest Brendan Banfield. (Fairfax County Police Department.)

She then reportedly called Brendan, a former criminal investigative agent for the IRS who had at that point left for work, and told him about the unknown car in their driveway. The pair decided to meet at the Banfields' home and walk inside together, as the Washington Post reported.

VIRGINIA AU PAIR CHARGED IN MAN'S MURDER AT HOME OF DOUBLE HOMICIDE: POLICE

Christine Banfield was stabbed to death in the bedroom of her Fairfax County, Va., home. (Facebook)

Initially, Magalhaes told police that when she and Brendan walked inside, they saw an unknown man, Ryan, holding Christine at knifepoint. She allegedly described him as an intruder. Ryan was apparently fully clothed while Christine was naked in the main bedroom of the house.

It remains unclear exactly what transpired inside the home that Friday morning, but Magalhaes and Brendan apparently both admitted to shooting Ryan while the man was holding a knife to Christine.

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Magalhaes is charged with second-degree murder and use of a deadly weapon during the commission of a crime. (Instagram)

Prosecutors allege that a computer at the Banfield home was tied to an account on a sexual fetish website, the Post reported.

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While the account on that computer appeared to show a photo of Christine in a bathing suit, it is unclear exactly who was communicating on the account. The profile also apparently did not display "one iota of evidence that she was into knife play, binding, BDSM," prosecutor Eric Clingan said in court, according to the Post.

Authorities eventually arrested Magalhaes in October 2023. (FOX 5 DC)

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Ryan, the man who held Christine at knifepoint, also apparently had an account on the website and had been communicating with whoever was accessing the site from the Banfield computer.

A framed photo of Brendan Banfield and Juliana Magalhaes and the mistress's lingerie were found in the room where the double homicide occurred, according to prosecutors. (Fairfax County Commonwealth Attorney's Office)

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Authorities eventually arrested Magalhaes in October 2023 after she moved in to the Banfields' main bedroom and placed a framed photo of herself with Brendan on a nightstand beside the bed. A grand jury indicted the 23-year-old in April, and her trial is scheduled to take place in November.

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Magalhaes' attorney, Ryan Campbell, did not respond to an inquiry from Fox News Digital. Brendan is no longer employed by the IRS, the agency confirmed.