The case turns on whether Banfield and the family’s Brazilian au pair, Juliana Peres Magalhães, orchestrated the killings and staged them as self-defense — or whether Christine Banfield herself arranged the fatal encounter, as digital forensic evidence introduced by the defense contends. Magalhães pleaded guilty in 2024 to a reduced manslaughter charge and gave investigators a statement that prosecutors say affirmed their theory; a competing forensic analysis, peer-reviewed by a University of Alabama team, concluded Christine Banfield made contact with the second victim on her own.
FAIRFAX, Va. — A northern Virginia man charged with killing his wife and another man in what prosecutors call an elaborate scheme to frame the second victim for his wife’s murder goes to trial Monday on aggravated murder charges, with the family’s Brazilian au pair already having pleaded guilty to a reduced charge.
Brendan Banfield faces two counts of aggravated murder in the February 24, 2023, deaths of Christine Banfield and Joseph Ryan at the Banfields’ home in Fairfax County. He has pleaded not guilty. The family’s au pair, Juliana Peres Magalhães, pleaded guilty in 2024 to a downgraded manslaughter charge and gave investigators a statement that prosecutors say affirmed their account of the killings.
Banfield is also charged with child abuse and felony child cruelty in connection with the case; his daughter was at the home the morning of the killings.
The prosecution’s account
Prosecutors say Banfield and Magalhães — whom authorities say had begun a romantic affair the year before the killings — created a social media account in Christine Banfield’s name on a platform for people interested in sexual fetishes. Through that account, prosecutors say, Ryan connected with the fake profile and arranged to meet on the morning of February 24, 2023, for a sexual encounter that would involve a knife.
Banfield and Magalhães told officials at the time that they witnessed Ryan, whom they described as a stranger, stabbing Christine Banfield after he entered the home, and that they each shot Ryan in self-defense, according to court records. Prosecutors contend the two staged that account.
In her statement to investigators, Magalhães said she and Banfield created the account in his wife’s name, authorities said. Prosecutor Eric Clingan said last year that the statement had resolved previously conflicting accounts among the investigators working the case.
“With 12 different homicide detectives, there were 24 different theories,” Clingan said. “Now, one theory.”
A contested digital record
Not all investigators have accepted the prosecution’s account. Brendan Miller, a former digital forensic examiner with the Fairfax County Police Department, testified 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. A former Fairfax County commander testified the reassignment was not punitive or disciplinary.
Defense attorney John Carroll argued that Miller’s transfer was directly tied to the case, and said the case’s lead detective was also reassigned after pushing back on the department’s theory of how Ryan came to be at the home.
“It is a theory in search of facts rather than a series of facts supporting a theory,” Carroll said of the prosecution’s account.
Banfield’s trial on the aggravated murder charges will run concurrently with the child abuse and felony child cruelty counts, according to court records.