Juju Chang

So Preston testifies that he and Liam mapped out every step of Sarah's murder, from how they'd get her to withdraw the money from the bank to timing a practice run at the bridge.

It was all calculated.

But when it's time for the defense to cross-examine Preston, Liam's attorney, Carlos Diaz-Cobo, questions his credibility.

He warns the jury, don't trust what Preston Taylor tells you.

He says Preston lied to investigators when they interviewed him after Sarah's disappearance, and again after his arrest.

The defense questions Preston about a statement he made while in custody.

Preston initially told investigators that he was sexually assaulted as a child.

But when detectives said they were going to look into his allegations, he took back his claim.

In an interview with ABC News in 2019, Diaz-Cobo said it's strange that Preston would lie about something like that.

In court, he argues that Preston has a history of lying.

The defense suggests that if Preston's lied in the past, who's to say he's telling the truth on the stand?

the prosecution pushes back.

They remind the jury that Preston's cooperation agreement hinges on Preston telling the truth, or else he could be facing felony murder charges.

Over the next couple of weeks, the prosecution calls more witnesses.

Michael Stern's in the court every day, listening to things no parent should ever have to hear about their child.

Until it's his turn to take the stand.

It's his chance to address the claims Liam and Preston made about his relationship with his teenage daughter.

Michael's wearing a black sweater over a gray plaid shirt that's peeking through the collar.

His bright blue eyes stand out even behind his glasses.

Assistant Prosecutor Megan Doyle starts her questioning by asking about Sarah's mother, Carla.