In 1970, people close to William Maxwell began to die in suspicious ways.

On a sweltering afternoon in September 1977, onlookers fanned themselves in an Alabama courthouse and waited for the jury to reach a verdict. The defendant was Robert Burns, accused of first-degree murder. In addition to the principal charges, three other elements made this particular trial extraordinary.

Firstly, the victim whom Burns was accused of slaying, William Maxwell, was himself a suspected serial killer. Secondly, Burns’s lawyer, a man named Tom Radley, was Maxwell’s lawyer when he was still alive. And perhaps most extraordinary of all, present at the proceedings was Harper Lee, the author who had penned the best-selling novel To Kill a Mockingbird 17 years earlier.

How did these remarkable circumstances arise? Well, to understand that, we must go back 7 years before the day of the verdict.

On August 1st, 1970, William Maxwell, an African American veteran of World War II, was living in Nixburg, Alabama, with his wife of 21 years, Mary Lou. Although Maxwell was a Baptist preacher, he was rumored to be less than virtuous in his spare time, and had a reputation for regularly cheating on Mary Lou.

But on the night of August 3, 1970, tragedy struck. According to the couple’s neighbor, Dorcas Anderson, Mary Lou got a late-night telephone call from Maxwell saying that he had crashed his car and needed her to pick him up. Worried about her husband, Mary Lou went to Dorcas’s house to tell her what had happened before rushing out to find him.

By the next morning, Mary Lou was dead. Her bruised and bloody body was found inside her car on a lonely stretch of highway. She’d been viciously beaten to death. Upon hearing Dorcas’s version of events, the police immediately suspected Maxwell of Mary Lou’s murder.

Maxwell claimed that Dorcas had it wrong. According to him, Mary Lou had actually gone out that evening to visit her sister. When she drove home, she had obviously encountered trouble that resulted in her death. But the police weren’t buying Maxwell’s version of events, and on August 6th, 1971, a grand jury indicted him for Mary Lou’s murder.