You've heard the expression that there are monsters amongst us and there just are.

And we get so carried away sometimes with the why, and I think we lose side of the fact that there really is evil in the world.

This was so diabolical, so evil.

It's really, it's hard to put into words.

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 murder.

What does it take for someone to commit murder? A motive? Sometimes.

Some level of cunning or deceitfulness.

Maybe.

But whatever traits are required to commit that ultimate act of cruelty,

it takes a special kind of evil to perpetrate violence against a family member

and a disturbing lack of remorse to try to get away with it again and again.

Back in September of 2005, a prosecutor in Syracuse, New York was challenged to answer these very questions

when he took on a case that began with an investigation into a local man's mysterious death and ended with the face-off against a possible serial killer.

Bill Fitzpatrick has been the elected district attorney in Onondaga County since 1992.

And like many public servants, we've met on the show, even from a young age, Bill seemed destined for the job.

It's actually a lifetime dream. My dad was a New York City cop, and I've always wanted to be a

prosecutor. I wish I could say I wanted to be a baseball player or an astronaut or something,

but actually since about the age of 11, I wanted to be a DA, and it's a dream come true for me.

I'm happy to say that I've known Bill professionally at this point for decades, and I can vouch

for both his dedication to law enforcement and his many talents as a prosecutor, which in part

...