The trial of Brendan Banfield, a former IRS special agent facing allegations of masterminding a brutal double homicide to cover up an affair with his family’s au pair, is set to commence with opening statements on Tuesday.

On Monday, a jury comprising twelve members and four alternates was selected to hear the case, as reported by FOX 5.

Banfield stands accused of aggravated murder in the tragic deaths of Christine Banfield and Joseph Ryan, which occurred in February 2023 at the Banfields’ residence located in the picturesque suburb of Herndon, Virginia, just outside Washington, D.C.

Court documents reveal that Banfield and Juliana Peres Magalhães, the 22-year-old au pair from Brazil, were present when his wife and Ryan were slain in the primary bedroom of the home. Initially, the au pair informed investigators that they had stumbled upon Ryan—a stranger—attacking Banfield’s wife and that they had shot him to halt the assault.

Brendan Banfield faces charges of four counts of aggravated murder and the use of a firearm during the commission of a felony, according to Fairfax County Police.

Prosecutors contend, however, that the reality was far more sinister. They argue that Banfield and Magalhães deliberately enticed Ryan to the residence and then staged the scene to make the killings appear as though they were committed in self-defense.

Prosecutors have said Banfield was impersonating his wife, Christine, in an online account on a fetish website. Prosecutors said the husband lured Ryan to the couple’s Herndon-area home as part of his plot to kill his wife.

“It is a theory in search of facts rather than a series of facts supporting a theory,” John Carroll, Banfield’s attorney, previously said.

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)

When police initially responded to a 911 call from the residence in February 2023, they found Christine with stab wounds to the neck and Ryan with fatal gunshot wounds in the upstairs bedroom of the home.

Authorities took Christine to the hospital, where she was later pronounced dead, Fairfax County Police Department Chief Kevin Davis said. Officials recovered a knife and two guns from the scene.

The account used to summon Joseph Ryan was made and used on slain mother Christine Banfield’s laptop – but investigators have questioned whether she was the one communicating on the account. (Christine Banfield on Facebook)

Banfield has pleaded not guilty in the case, but Magalhães, a Brazilian national, pleaded guilty to manslaughter in late 2024.

She is expected to testify against Banfield during the trial and provide a first-hand account of the alleged plot.

Fairfax County police initially responded to the double homicide in the 13200 block of Stable Brook Way in Herndon on Feb. 24, 2023. (FOX 5 DC)

GET REAL TIME UPDATES DIRECTLY ON THE TRUE CRIME HUB

If convicted, Banfield is expected to face life in prison. Fox News Digital has reached out to Banfield’s attorney, John Carroll, for comment.

The trial is expected to last four weeks. Court sessions will begin at 10 a.m. each day and run Monday through Thursday, according to court administrators.