Here’s what we know about the case.

Police found an ‘appalling’ murder scene

On the morning of February 24, 2023, police officers responded to 911 calls placed by Magalhaes, and found a scene they would later describe as “appalling”.

In a large home on a cul-de-sac, they found Banfield’s wife, a paediatric nurse, who had been stabbed in the upper body and would soon die of her injuries, and Ryan, who had been shot dead. Banfield, Magalhaes and Banfield’s four-year-old daughter were also at the scene, unharmed.

Banfield and Magalhaes told police that Ryan was attacking Christine Banfield that day and they were trying to defend her. But police found no sign of forced entry, and prosecutors said the man who was shot had been invited to the home for a sexual tryst.

Police recovered a knife and two guns.

The au pair fired a weapon, too

Magalhaes started her job as a live-in childcare worker for the Banfields in 2021.

On the morning of the killings, Magalhaes said she set out with the couple’s daughter sometime after 7am for the zoo, but returned after forgetting their lunch, according to her lawyers, who gave her account of events at a hearing in April.

She saw an unfamiliar car outside the home and called Christine Banfield, who did not pick up. She then called Brendan Banfield, and once he arrived, they went inside together, the lawyers said.

Magalhaes took the child to the basement but heard a commotion and went upstairs, the lawyers said, where Brendan Banfield was shouting, “Drop the knife!”

Banfield told a 911 operator that a man was stabbing his wife, and that he fired his service weapon at the man to stop him. Magalhaes later told a detective that Banfield told her to get a second gun from a bathroom, giving her the code to a safe.

She retrieved it and fired, the lawyers said, arguing that she was acting in self-defence to protect the family. They later emphasised that she was acting on orders from her employer.

Ryan, of Springfield, Virginia, was pronounced dead at the scene. A medical examiner testified that he was struck twice, in the head and chest, and that it was the shot to the chest – the au pair’s bullet – that was the fatal shot.

Who was the man shot in the Banfield home?

Prosecutors say Ryan exchanged messages with a profile featuring a photograph of Christine Banfield on the website FetLife, which describes itself as a community for people interested in kinky sexual practices.

It was not clear who had created the profile.

Ryan had arranged to come to the Banfield home after discussing plans for “rough sex”, prosecutors said.

Ryan was open about his activity on FetLife, his friend told The Washington Post.

People who knew Christine Banfield said the messages discussing a rendezvous did not sound like her, and a prosecutor, Eric Clingan, said in April that there was no evidence that she had been “into knife play, binding” or other similar sexual practices.

But Magalhaes’ lawyers have emphasised that it was Christine Banfield who purchased tickets for her daughter and au pair to go to the zoo that day, suggesting she wanted to have the house to herself.

Allegations of an affair

While prosecutors have not said that Magalhaes and Brendan Banfield concocted a plot to frame Ryan, they have offered a possible motive: the two had been having a months-long affair.

In October 2023, when police returned to the Banfield home with a warrant to arrest Magalhaes, they found that she had moved into the master bedroom with her employer, the same room where Christine Banfield was stabbed eight months earlier.

Magalhaes’ clothes were hanging in the closet and her lingerie was strewed around the bed, according to photos introduced at a hearing. A framed picture of the two had been propped on the bedside table.

Her lawyers have said that she was Brendan Banfield’s “girlfriend”, but claim that neither of the Banfields were sexually exclusive.

In April, prosecutors revealed that the pair practised shooting at a gun range two months before the killings, and that Banfield later returned to the range and purchased a pistol – the Glock with which Magalhaes shot Ryan.

This article originally appeared in The New York Times.