THE DARK SIDE OF A BAPTIST PREACHER IS EXPOSED AFTER THE SUDDEN DEATH OF HIS YOUNG WIFE -- WAS SOMEONE PLAYING GOD? NOW THE OTHER WOMAN SHEDS NEW LIGHT ON THE PREACHER WHO COMMITTED THE ULTIMATE SIN -- A "48 HOURS MYSTERY," DOUBLEHEADER ON SATURDAY, OCT. 30

Since the sudden death of his wife Kari in April 2006, Matt Baker has gone from grieving husband to a murder suspect maintaining his innocence to convicted killer. And it was his lover, Vanessa Bulls, who revealed the dark secrets that helped put him behind bars. With exclusive interviews, police videos and depositions, correspondent Erin Moriarty reports in a 48 HOURS MYSTERY doubleheader on Saturday, Oct. 30, with "The Preacher's Wife" (9:00-10:00 PM, ET/PT) and "Dirty Little Secrets," (10:00-11:00 PM, ET/PT) on the CBS Television Network.

Kari Baker was a beloved school teacher who shared a seemingly perfect life with her husband Matt, a pastor. But the couple suffered a devastating blow when one of their daughters succumbed to cancer shortly after her first birthday. According to Matt, Kari became withdrawn, leaving him struggling to take care of his family. Then, seven years later, tragedy struck again when Matt discovered Kari's lifeless body in the couple's Waco, Texas, home.

Although her death was ruled a suicide by authorities, Kari's family was convinced she had been murdered and set out to prove it by launching an investigation. Soon a very different portrait of the Baptist preacher known to the community began to emerge - one of man who cheated on his wife and whose account of her death was filled with contradictions.

Matt Baker denies these claims, but at the urging of her family and armed with new information, authorities reopened the investigation into Kari's death and soon Matt's story began to unravel. Then in bombshell testimony before a grand jury, Vanessa Bulls, revealed that Matt told her "I killed her for you." He even told her how he did it. It was exactly what prosecutors needed. Matt Baker was arrested and charged with Kari's murder but another shocking story was about to come out at trial-- Vanessa Bulls testified that Matt told her the exact date Kari would die. Yet she told no one.

Several excerpts from interviews that 48 Hours correspondent Erin Moriarty had conducted with Matt Baker before he was indicted, were shown at trial, which prosecutors said demonstrated how Baker's story repeatedly contradicted itself. When Baker's lawyer learned that his client had lied to him about the affair, he no longer trusted Baker and in a highly unusual move asked to be removed from the case. The judge forced him to stay on the case.

After seven hours a jury returned with a guilty verdict. It was a relief to Kari's family, who tirelessly pursued justice on her behalf. But the battle isn't over, as Kari's family fights for custody of her daughters, who currently live with Matt's parents.

This broadcast is produced by Gail Abbott Zimmerman. Lisa Freed and Judy Tygard are the senior producers. Doreen Schechter, Michael McHugh and Diana Modica are the editors. Al Briganti is the executive editor. Susan Zirinsky is the executive producer.

CBS News 48 HOURS MYSTERY broadcasts are now available on iTunes.com.