(NBC) — Friday on “Dateline,” the death of a beloved chiropractor becomes a criminal investigation when authorities discover she’d been poisoned.

Andrea Canning reports on a dramatic update in the case, including interviews with the woman convicted and the victim’s family.

Here is a preview of Canning’s report:

Mary Yoder, a successful chiropractor, had been feeling perfectly fine when the day began — by late afternoon she had grown violently ill. Now, she was gone.

JANINE KING: From the moment Mary died, we felt something’s not right.

What killed Mary Yoder? Perhaps the real question was, “Who?”

DETECTIVE NELSON: We were looking at it as a homicide.

CATHY CONLEY: Never ever in your wildest dreams would you think that this would happen.

A case a decade in the making and now, a new ruling and new questions.

ROCCO LADUCA: It all just really came out of the blue.

MELISSA SWARTZ: Maybe this isn’t the slam dunk case that some people think it is.

ROCCO LADUCA: A lot of people’s heads are spinning with all of this.

The two-hour episode “Dateline: Poison Twist” airs Friday at 9 p.m. on NBC4.