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Brendan Banfield’s attorneys challenged the origins and handling of the police theory behind his aggravated murder charges Thursday, questioning when Fairfax County investigators settled on their explanation for the February 2023 killings of Christine Banfield and Joseph Ryan.
Prosecutors allege Banfield and his family’s au pair, Juliana Peres Magalhães, plotted to kill Christine and frame Ryan. They say the pair impersonated Christine on a fetish website and lured Ryan to the family’s Herndon home, creating a scenario in which Banfield could claim he interrupted a home invasion.
Magalhães, who was having an affair with Banfield, was initially charged with murder. She pleaded guilty to a reduced manslaughter charge in 2024.
On the second day of the defense case, attorney John Carroll sought to support his opening argument that police struggled to find evidence matching the prosecution’s “catfishing theory.”
Detective Matthew Nilssen, testifying for the defense, said Magalhães was arrested on a murder charge well before she disclosed her involvement to prosecutors.
“Based on our investigation, there was a belief that there was more to the story that could be elicited from her,” Nilssen said. He explained that creating circumstances favoring cooperation with law enforcement over loyalty to others could change both the investigation’s outcome and the information available to detectives.
Homicide detective Leah Smith testified that investigators received a briefing one week after Christine and Ryan were killed. According to Smith, a supervisor said there were two theories and investigators needed to determine which one was correct.
Smith said the supervisors did not explain the details of the catfishing theory. She recalled telling the supervisor and the other investigators that it was too early to embrace any theory and that they should remain focused on gathering facts and information.
When Carroll asked how her superiors responded, Smith said there was no reaction.
The defense also questioned several witnesses about the removal of Brendan Miller, the case’s original lead investigator.
Patrick Brusch, now deputy chief of major crimes and a captain in 2024, said he decided to transfer Miller after the detective submitted an executive summary concluding that Christine never lost control of her phone or laptop.
That conclusion conflicted with the prosecution’s allegation that Banfield and Magalhães used Christine’s devices to communicate with Ryan and other men while arranging the purported setup.
After reviewing his own texts and emails in court, Brusch said he had directed that Miller no longer work on digital forensic cases involving the Major Crimes Bureau.
Smith testified that pressure from supervisors did not alter her approach. She said she would continue investigating and advising other detectives based on the evidence, regardless of the theories others wanted to advance.
During cross-examination, prosecutor Jenna Sands asked Smith what she remembered as the turning point that led to Banfield being charged.
“When we got the blood evidence back,” Smith replied.
Lt. David Giaccio identified that evidence as Christine’s blood, which investigators found on Magalhães’ socks and Banfield’s jeans. He said the account Magalhães later gave detectives aligned with the forensic evidence already collected.
“I think she filled in the blanks,” Giaccio said.
Fairfax County Circuit Court Chief Judge Penney Azcarate told jurors the trial was progressing quickly but was expected to continue into the following week. Jurors said Thursday that they were willing to hear testimony Friday in hopes of finishing testimony before winter weather expected over the weekend.