We get a lot of, you know, what we call just run-of-the-mill murders.

I think that she is obsessed with Sam.

It's very rare that you get a case that is actually planned out and executed.

Sam did not care for this girl.

It's one of the most devious murder cases.

We have to put it out there.

Because I do think she is a psychopath.

I think she had something to do with this.

I really, really think she did.

I'm Scott Weinberger, investigative journalist and former deputy sheriff.

I'm Anna Sige-Nikolazi, former New York City homicide prosecutor

and host of investigation discoveries through conviction.

And this is an anatomy of murder.

Welcome to San Antonio, Texas.

The date is January 17, 2010.

And Sergeant Lisa Miller is at the San Antonio Police Station about to come across a case.

That's going to reveal disturbing lies and secrets, not only within her community,

but also within her own police department.

It was a Sunday.

I was the only homicide detective working that day.

Figure that in a city of a million people.

And it was late in the evening, probably after five.

...