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48 Hours: A son's courtroom showdown with his father

SALT LAKE CITY, Utah -- Imagine being 21 and having a front row seat to a murder trial. Now imagine the defendant is your own father and the murder victim, your mother. For Pelle Wall, this haunting scenario is his reality.

On Feb. 18, 2015 young Pelle Wall took a seat in the gallery of the Salt Lake City courtroom, where for the next four weeks his father Johnny Wall would stand trial for the murder of his ex-wife and Pelle's mother, Uta von Schwedler.

This was a day Pelle had been waiting for with much anticipation. From the beginning, Pelle Wall had been convinced that his father was responsible for the murder of his mother.

Four years earlier, Uta von Schwedler was found dead in her bathtub with stab wounds on her wrist and leg and the drug Xanax in her system. Also in the tub was a knife and a prized photo album.

Detectives initially deemed the death a suicide, but the combination of a dogged detective and consistent pressure from Uta's friends and family caused the case to be re-opened as a homicide.

The prime suspect? Uta's ex-husband, Johnny Wall, a respected pediatrician. Looking back, the former couple had a tumultuous history.

Preview: Father and Son: The Verdict

Johnny Wall and Uta von Schwedler had been married for over 15 years before their divorce, which resulted in a bitter custody battle over their four children. It got so out of hand that the couple even fought over ownership of the family photo albums.

In the weeks leading up to Uta's death, the custody battle had gone from bad to worse and there was a real threat that Johnny could lose custody of their children. Years later, this fact would become the prosecution's theory of motive during Johnny Wall's murder trial.

In the days following Uta's death, Pelle Wall grew suspicious of his father, questioning Johnny about an unusual eye injury and his mysterious absence the morning before Uta's body was found. Pelle began to fear that he and his siblings were living with a murderer, and just a day before his 18th birthday, Pelle moved out.

Once Pelle was out from under Johnny's roof, he launched a full blown campaign and legal attack to take custody of his siblings away from his own father. And he eventually won.

Deposing Johnny Wall: "Did You Kill Uta?"

In the next legal foray between father and son, Pelle filed a wrongful death suit against Johnny Wall which resulted in his father being deposed. That deposition led to Johnny's eventual arrest in April 2013, and he was charged with his ex-wife's murder.

Pelle describes this day as exhilarating and a huge relief, but on the other side of the family Johnny's sister Wendy Wall was devastated. She regrets everything her nephew has done and maintains her brother's innocence.

Wendy says Johnny had nothing to do with Uta's death and her death was most likely the result of suicide. Johnny's defense attorney Fred Metos strategized a defense based on the theory that Uta grew depressed and committed suicide.

Fast forward to February 2015, and the murder trial of Johnny Wall is under way. His son Pelle Wall is the star witness in the case and knows his father won't have warm feelings for him when he eventually takes the stand.

For Pelle, the feeling is mutual.

Aimée deSimone is a producer on Saturday's new "48 Hours" episode, "Father and Son: The Verdict," which reports on the death of Uta von Schwedler and the verdict in the case against Johnny Wall. It airs Saturday at 10 p.m. ET/PT on CBS.