MADISON COUNTY, IL (KTVI-FOX2now.com) - It was one of the most infamous murder cases in the history of Madison County, Illinois. A woman named Barbara Gusewelle Boyle was in on the killing of her husband's parents, then took part in killing him. Now, 25 years later, she is quietly paroled from a 50-year prison sentence. Retired Judge Don Weber says, "She knew what was going on the whole time. She was just a mean, evil woman."

Former Madison County State's Attorney Don Weber cracked the Barbara Gusewelle Boyle triple murder case. He tied her in with a dentist convicted of multiple murder-for-profit schemes – Doctor Glennon Engleman.

With Gusewelle's knowledge, he went to the home of her mother and father-in-law near Hamel, Illinois, back in 1977. Weber explains, "He put them down on the kitchen floor, tied their hands behind them and shot them both, execution style."

After Gusewell Boyle and her husband Ronald collected the half-million in insurance, she went into action again. Two years later, after escalating Ronald's insurance coverage, she brought the deadly dentist in again, directing him to the garage of their home.

Weber says, "Engleman shot him and as Ron fell to the floor, Engleman took about a 3-pound hammer and also broke his skull and it killed him." They dumped Ron Gusewelle's lifeless body outside a motel in East St. Louis.

In 1985, Gusewell Boyle – defended by noted counselor F. Lee Bailey – was convicted for her role in the murder and sentenced to 50 years in prison.

Engleman died in a Missouri prison in 1999.

Six days ago, without fanfare, Barbara Gusewelle Boyle walked out of the Dwight Correctional Facility – her sentence had been reduced by half.

Weber says her actions at her husband's funeral spoke volumes about her nature, "At the funeral, when she didn't have any place to put her Pepsi can, she put her Pepsi can on the coffin as people were coming past. She was cold-hearted."

Cutting the sentence in half was possible because Illinois' "truth in sentencing" law was not in effect at the time of her conviction.

The 67-year-old woman has just begun residing in a halfway house in northern Illinois. She'll be on parole for three years.

Efforts to reach her were unsuccessful.