Gertrude Nadine Baniszewski was born on September 19, 1928, in Indianapolis, Indiana. Her parents were Hugh Marcus Van Fossan Sr. and Molly Myrtle Oakley. Both of her parents were originally from Illinois and had English and Dutch ancestry. Gertrude was the third of six children in a working-class family.

In 1939, when Gertrude was 11 years old, her father died suddenly from a heart attack. This event had a significant impact on her and her family. At the age of 16, Gertrude dropped out of high school to marry an 18-year-old named John Stephan Baniszewski, who was of Polish descent and from Youngsville, Pennsylvania. They had four children together.

Gertrude's marriage to John was troubled. He had a volatile temper and sometimes physically abused her. Despite this, they stayed married for about ten years before divorcing. After the divorce, she married another man named Edward Guthrie, but this marriage lasted only three months. Gertrude then remarried her first husband, and they had two more children, but they divorced again in 1963.

After her third divorce, Gertrude began a relationship with a 20-year-old welder named Dennis Lee Wright. This relationship was also marked by abuse. She and Wright had one child, Dennis Lee Wright Jr., but he left soon after the boy was born in May 1964. Gertrude filed for financial support from Wright, but he did not contribute much to raising their son.

By 1965, Gertrude was 36 years old and living alone with her seven children. They included Paula, Stephanie, John, Marie, Shirley, James, and the infant Dennis. At this time, she was described as thin and suffering from health problems such as asthma and depression. She struggled to support her family financially, relying on occasional support from her ex-husband and doing odd jobs like sewing and cleaning for neighbors.

Gertrude lived in a modest rental home in Indianapolis. The family faced many challenges, and the stress of her past relationships and financial struggles weighed heavily on her.

In July 1965, Sylvia Likens and her sister Jenny began living with Gertrude Baniszewski after their parents were unable to care for them due to financial issues. Initially, the sisters experienced no significant problems. However, as time passed, Gertrude became increasingly abusive, particularly towards Sylvia.

By August, Gertrude's anger grew because the weekly payments for the sisters' care were often late. Sylvia was subjected to physical punishment, including beatings with a paddle. As Gertrude's abuse escalated, she focused her rage on Sylvia, who was often humiliated, starved, and forced to eat spoiled food from garbage cans. Gertrude also involving her children and neighborhood kids in the torment, turning them into willing participants in the cruelty.

During this time, Sylvia was accused of petty offenses and subjected to extreme punishment. She faced beatings for real or imagined misdeeds, such as stealing food or rumors about her behavior with boys. Gertrude would often force Jenny to participate in the abuse, inflicting psychological torment on both sisters.

The situation deteriorated further when Gertrude locked Sylvia in the basement for extended periods, often depriving her of food and water. Sylvia's condition became increasingly dire, leading to incontinence, which further incited Gertrude's wrath. The abuse peaked in October when Gertrude and her children inflicted severe physical injuries and humiliation upon Sylvia.

On October 25, Sylvia attempted to escape but was caught and brutally punished. By the following day, her health had severely declined. Despite attempts to feed her, Sylvia was unresponsive and could barely move. As her tormentors continued to mistreat her, Sylvia ultimately succumbed to her injuries on October 26, 1965.

After her death, Gertrude and several others in her household attempted to cover up the crime. When authorities arrived, they were led to Sylvia's lifeless body and were presented with a letter Gertrude had forced Sylvia to write, falsely claiming she had run away and was hurt by boys. This act of deception ultimately led to the arrest of Gertrude Baniszewski and her accomplices.

An autopsy revealed that Sylvia had suffered over 150 wounds, along with severe malnutrition. The subsequent trials exposed the horrific nature of the abuse she endured, leading to first-degree murder charges against Gertrude and her co-defendants.