If you were to give advice to someone that's about to start working homicides, what would it be?

One, have someone not involved in law enforcement that you can talk to.

You can vent to go out and just get a different perspective on things.

And the other advice I'd give you is don't worry on the why it happened.

Figure out the who, what, when, where, and how and leave the why to somebody else.

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 Anatomy of Murder.

For today's story, I spoke with Detective Mike Kirby from Willing, Illinois.

Mike has what we call a deep lineage to law enforcement.

Generations of family members taking the oath to serve.

My father, after World War II, was a railroad policeman for the Illinois Gulf Central railroad before he created a private investigator firm.

His dad was a sheriff in Texas and his grandfather was a Texas Ranger.

And even though Mike has now retired, he has passed that torch most recently to his son.

He's continuing in law enforcement. He's the sixth generation there.

A few years into his career, Mike was chosen for the North Regional Major Crimes Task Force,

where he would work over 100 homicides in the next 10 years.

A task force really talks to the strength in numbers.

You know, you draw upon different insights, different areas, expertise,

and you're able to work on multiple avenues all at the same time.

To me, this case is the poster case for task force.

One small agency, even Wheeling, we had six detectives,

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