WHY WOULD A POPULAR BAPTIST MINISTER MURDER HIS WIFE? JIM AVILA'S REPORT AIRS ON "20/20," FRIDAY, JULY 9 AT 10:00 PM ET

Was the untimely death of a Baptist preacher's wife really a suicide as the justice of the peace first ruled or was Kari Baker, a perfectly healthy mother of two, murdered� by her husband? Kari's family's persistence in keeping the case alive, finding another woman and suspecting foul play, ultimately led to her husband Matt's arrest, and then conviction. For the past two years, "20/20" has been following the twists and turns, including revelations made by the woman, who after months of lying, admitted to having an affair with Matt while Kari was still alive. She tells the court specifically how Matt plotted and eventually carried out the evil plan.

In an exclusive television interview from prison, ABC News Correspondent Jim Avila talks to Matt, the popular Baptist minister from Waco, Texas, convicted of murdering his wife and staging it as a suicide. The report airs on FRIDAY, JULY 9 (10:00 - 11:00 p.m. ET) on the ABC Television Network.

"20/20" is anchored by Elizabeth Vargas and Chris Cuomo. David Sloan is executive producer.