This is Hidden Killers Live with Tony Bruske, Stacey Cole, and Todd Michaels.

The prosecution's entire case here in the Au pair affair murder trial that's getting underway of Brennan Banfield.

It comes down to one person, Juliana Perez Mangalese.

She spent a year in jail facing second-degree murder charges.

Then she changed her story, took a plea deal for manslaughter with time served and agreed to testify

against the man she allegedly helped commit double murder. She gets to go home to Brazil. All she

has to do is say what prosecutors need her

to say. But here's the thing. From a jail cell, she wrote to her mother. And she was heartbroken

for what she was doing to Brendan, that she still loved him. So how does the juryway testimony

from a witness whose freedom depends entirely on conviction?

Jennifer Coffendaff, a retired FBI special agent, is here to help us break all that down.

The sentencing is scheduled for after Banfield's trial. This is the scheduling for Juliana,

meaning nothing or go back to Brazil, to ensure that she continues to cooperate.

I mean, essentially that means to ensure that she continues to say what we want her to say.

If she doesn't say what we want her to say, they could say you're not going back home.

I mean, this, again, it just, this doesn't feel like the free will of a witness in a case like this when you're holding literally her future in front of her.

And Tony, that happens every day in every investigation from the standpoint of we get witnesses that are jailhouse snitches.

We get witnesses. Look, you can't get choir boys to talk about gangbanging or to talk about

murders, right? It's people who have their hands dirty in one way or the other in terms of the

crime because those are the witnesses to them, right? So you have to take into account,

in my opinion, how does she hold up on the stand? How does she do in terms of what she said?

It's always a problem when you have anyone change in their testimony. I mean, for me, geez, it's, it's tough. I mean,

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