Northern Virginia

Search warrant details jail conversations of au pair accused in Herndon double-murder

Prosecutors say Brendan Banfield and his au pair, Juliana Peres Magalhaes, were having an affair for months before the killings

NBC Universal, Inc.

An au pair accused in a double-murder in Northern Virginia was in close contact with her alleged lover and his mother after her arrest — and police believed his mother might have been passing messages to the au pair, documents reveal.

Juliana Peres Magalhaes and Brendan Banfield, the father of the family for whom she worked, are accused of working together to kill Banfield's wife, Christine Banfield, and a stranger, Joseph Ryan, inside the married couple's Herndon home in February 2023.

In a search warrant affidavit obtained by News4, investigators detailed recorded conversations between Peres Magalhaes and Banfield's mother, Teresa Banfield.

Detectives wrote that Peres Magalhaes communicated with Brendan and Teresa Banfield almost daily after she was jailed, either by phone or by texting and emailing with a jail tablet. The jail closely monitors both.

Detectives report that recordings reveal both Banfields warned Peres Magalhaes not to talk about the alleged crimes since the phone calls were recorded.

In one phone call, Teresa Banfield told Peres Magalhaes she’d been texting with one of the defense attorneys, who offered to make a delivery during a jail visit, according to the search warrant.

The document states Teresa Banfield then read the text aloud to Juliana. “Hi Tess. I will be going to visit Juliana this morning. Expected to be there around 9. If I, you know, if I have anything I’d give it to her," the affidavit said.

Detectives wrote that in the call, Teresa Banfield said she complained to the attorneys that some “things” were not getting to Peres Magalhaes and told them: “It’s the only way we can communicate with her about what’s happening.”

The defense attorney for Peres Magalhaes denied helping his client get any type of correspondence to Brendan Banfield or his mother.

Lawyers for Juliana Peres Magalhaes wanted some of her statements to Fairfax County police thrown out News4's Juliana Valencia reports.

A double killing

It was around 7:30 a.m. on Feb. 24, 2023, when Peres Magalhaes left the Banfields' Stable Brook Way home with their 4-year-old daughter, according to detectives. The 23-year-old told police she doubled back to the home because she forgot to grab packed lunches. When she arrived, Peres Magalhaes, a Brazilian-national who also lived in the home, saw a car she didn't recognize.

She called Christine, but when the mother didn't answer, Peres Magalhaes phoned Brendan, who quickly came home, authorities said.

Minutes later, the pair and the child entered the home. Brendan then went upstairs to the bedroom where he found Christine and Ryan.

Detectives say the two claimed Ryan had attacked Christine, prompting Brendan — a law enforcement officer for the Internal Revenue Service — to fire his weapon at Ryan.

Ryan had no obvious connection to the family or home other than the incident that cold winter day. But as detectives began probing how he supposedly found Christine, their case and the witness statements started to diverge.

A fetish site used as a lure?

A search of a computer in the Bandfields' home led detectives to a fetish sex website, prosecutors said. The site catered to sexual fantasies involving kinks, BDSM, and more.

Prosecutors said Brendan Banfield and the au pair concocted a plan to use the sex fetish website to lure Ryan to the home.

Detectives found a profile for Christine and communications between her profile and Ryan. But authorities said something didn't add up.

They said the way Christine talked to Ryan in their messages was very different than how friends and family described her.

Police believe someone else was communicating with Ryan while pretending to be Christine — setting a meetup at the family's home for that day.

Nearly eight months after the killings, Fairfax County authorities arrested Peres Magalhaes and charged her with second-degree murder in Ryan's death.

Brendan Banfield was indicted in the murders of his wife and Ryan in September, nearly a year after Peres Magalhaes was arrested.

Photos the prosecution previously presented show Brendan Banfield with Peres Magalhaes in New York and at a concert venue. The two were involved in an affair for months before the killings, prosecutors said.

More photos show Peres Magalhaes at a Virginia gun range, and attorneys also presented visitor logs of Banfield and Peres Magalhaes at the gun range.

While arguing that the couple had plans to flea the country, the prosecution showed photos of a new Brazilian passport for the au pair. Attorneys said Banfield drove Peres Magalhaes to the Brazilian consulate to apply for a new passport.

Contact Us