The Blood Doesn't Lie

1 in 8.1 billion.

That's the probability of randomly selecting someone other than Christine Banfield whose DNA would match the blood found on her husband's jeans. Six spots of blood. All matching the woman who was stabbed to death in their bedroom. The same blood was inside the au pair's sneaker inserts. Under Joseph Ryan's fingernails. On the knife that killed her.

The DNA analyst, Kathryn Colombo, spent nearly an hour walking the jury through evidence that tells a story the defense will have to explain away. And I'm not sure how they do it.

The Blood Map

Let me walk you through what the jury learned today.

Christine Banfield's blood was on the knife. Sharp edge. Heel of the blade. 1 in 7.2 billion odds it's anyone else. Brendan Banfield, Juliana Peres Magalhães, and Joseph Ryan were all eliminated as contributors.

Six blood spots on Brendan's jeans. Five on the front right leg, one on the rear waistband. All matching Christine. 1 in 8.1 billion. When the prosecutor asked about minor DNA found in what appeared to be single blood drops, the analyst explained she had to cut through the fabric to collect samples, so trace DNA from the inside of the pants might have been detected. Those pants were being worn when police collected them.

Juliana's shoes told another story. Sixteen blood stains on the exterior. But here's what matters: blood was found inside the sneaker inserts. Not on the bottom of the shoe from walking through the scene. Inside. Two red-brown stained areas on the left insert, matching Christine at 1 in 8.1 billion.

Think about that. How does blood get inside your shoe unless you're standing in it long enough for it to seep through?

The Affair, Proven in DNA

The prosecution has alleged from the start that Brendan Banfield was having an affair with the family's au pair, Juliana Peres Magalhães. That this affair was the motive for murder. That Brendan wanted to be with her and needed Christine out of the way.

Today the jury saw the proof.

Five stained areas on the fitted sheet from Juliana's bedroom. Sperm cells identified in all five. Brendan Banfield could not be eliminated as the contributor. 1 in 7.2 billion. The non-sperm fraction contained a mixture of DNA from both Brendan and Juliana. Christine and Joseph Ryan were eliminated.

That's not speculation. That's not allegation. That's biological evidence of a sexual relationship between the defendant and the woman prosecutors say helped him plan his wife's murder.

What This Means

The State's theory is that Brendan Banfield orchestrated the killing of his wife so he could be with another woman. They say he created a fake profile to lure Joseph Ryan to the house, shot Ryan in the head, stabbed Christine with Ryan's knife, and staged the scene to look like a home invasion.

The DNA evidence doesn't prove that theory. DNA can't tell you who swung the knife. But it puts Christine's blood on Brendan's clothes, inside the au pair's shoes, and proves the affair that the prosecution says drove everything.

The defense will argue transfer. They'll point to the chaos of the scene. They'll note that Brendan was wearing those jeans when he found his wife being attacked, so of course there might be blood on them.

But six spots? Inside Juliana's shoes? And the sperm on her sheets?

The jury will have to decide what story the blood tells. But standing here on Day 3, watching the evidence pile up, I can tell you this: the prosecution is building something methodical. Something devastating. And the defense has a lot of explaining to do.

▶️ WATCH NOW DNA Expert: 1 in 8 Billion Chance the Blood on Husband's Jeans Wasn't His Wife's

Brendan Banfield is presumed innocent until proven guilty. That's not a formality. That's the foundation. But the evidence the jury heard today is the kind that stays with you. The kind that's hard to unsee.

1 in 8.1 billion. The blood doesn't lie.