About an hour until the interview was when I asked him about the needle pricking in her elbow crease.

Joel, why is that there? I don't know. I asked them point blank that night.

Joel, did you inject your wife with anesthesia?

What? No, I love her. I love her.

I'm Scott Weinberger,

investigative journalist and former deputy sheriff.

I'm Anasiga Nikolazi,

former New York City homicide prosecutor

and host of investigation

discoveries true conviction.

And this is Anatomy of Murph.

All marriages have their ups and downs, and most couples will tell you that it takes a lot of

patience and hard work to make a healthy partnership endure.

When times do get tough, there are numerous ways to cope, from confiding in friends and family,

to couples therapy to keeping a private journal, all of which can be powerful tools for healing.

And in some cases, powerful testimony to a person's

emotional state or the state of a struggling marriage. But of course, some marital discord can

prove too challenging to overcome, especially when it comes to infidelity, abuse, or other trauma.

And in those cases, a record of a couple's problems does not just become a window into their

private lives. It can become evidence.

My name is Luis Mata Jr. I am a sergeant of the Laredo Police Department's crimes against persons robbery and homicide bureau

here in the Laredo Police Department in Laredo, Texas.

...