Sylvia died on October 26th 1965 in Indianapolis, Indiana, United States. She died of a brain hemorrhage, shock, and malnutrition following three months of physical abuse and torture at the hands of Gertrude Baniszewski, Gertude’s children, and other neighbourhood children. Gertrude was left to take care of Sylvia and her younger sister Jenny in exchange for $20 a week by the girls Parents, who worked on the carnival circuit. Gertrude was a haggard, underweight asthmatic who was suffering from depression, following several failed marriages. Once when her $20 check was late Gertrude blamed the Likens sisters and spanked them on the behind with a paddle. The check came the next day. Gertrude started to focus her abuse exclusively on Sylvia. She would accuse sylvia of stealing sweets and food and would humiliate her at every opportunity. Gertrude’s Daughter, Paula who was pregnant at a the time by a married man, would get involved in the abuse and kicked Sylvia in the genitals and accused her of being pregnant. Gertrude allowed her children to beat Sylvia and would repeatedly kick her down the stairs for their own amusement. Gertrude, Paula and one of the neighbour boys made Sylvia eat a hot dog overloaded with condiments. It made her sick and later she was made to consume her own vomit. Gertrude also accused Sylvia of prostitution and would deliver misogynistic sermons about the filthiness of prostitutes and women in general. Sylvia was accused of spreading rumours around Arsenal Technical High School that Paula and Stephanie Baniszewski were prostitutes. This provoked Stephanie's boyfriend, Coy Hubbard, to physically attack Sylvia. Coy and his classmates soon made frequent visits to the Baniszewski home, and with Gurtrude’s encouragement, they beat on Sylvia and forced her to eat feces and drink urine. They also used her to practice judo sessions on. They burnt her body with lit cigarettes over 100 times and severely injured her genitals. To entertain Gertrude and her teenage accomplices, Sylvia was forced to strip naked in the living room and insert an empty Coca-Cola bottle inside herself. Paula once beat Sylvia in the face so hard that she broke her own wrist. She later used her arm cast to further beat Sylvia. Gertrude later forced Jenny to also hit her sister, beating her if she didn’t do it. Gertrude eventually forbade Sylvia from attending school after she confessed to having stolen a gym suit from the school. Gertrude brutally beat and whipped Sylvia and did the same for Jenny after remembering that she supposedly stole tennis shoes. Gertrude then switched the topic to the "evils" of premarital sex and brutally kicked Sylvia repeatedly in the genitals and then burned all of her fingers with matches. Sylvia eventually became incontinent but she was denied access to the bathroom and she was forced to wet herself. As punishment for her incontinence, Gertrude threw her in the basement. Gertrude, with the assistance of her children and their friends, would restrain Sylvia in a bathtub filled with scalding water and rubbed salt onto her burns. She was often kept naked and hardly ever fed. Sometimes Gertrude and her twelve-year-old son John Jr. would make Sylvia eat her own feces, as well as urine and feces from the dirty diapers of Gertrude’s one-year-old son. Abusing Sylvia became Gertrude’s favourite pastime activity and she charged the neighbourhood children five cents to see Sylvia naked and to tie her up and beat, burn and mutilate her. Sylvia tried to alert the neighbours by screaming for help to no avail. The Likens sisters had no way of contacting family members to inform them of the abuse. Jenny was constantly threatened by Gertrude that she would be abused and tortured next to her sister. She was also bullied by the neighbourhood kids and beaten whenever she complained about Sylvia's situation. Nonetheless, they encountered Diana, their older, married sister, at the local park. Diana was forbidden by her parents to make contact with the sisters due to her estrangement, Diana eventually learned that Sylvia and Jenny were staying at Gertrude’s home and she attempted to visit them. Upon her visit, Gertrude told Diana, unaware of who Gertrude was, that the Likens sisters were not allowed to see her and ordered her off her property. At one point, Diana secretly gave a Sylvia a sandwich. Sylvia kept quiet about the matter but after Marie Baniszewski told on her to Gertrude, Paula and Gertrude choked and paddled Sylvia before subjecting her to another scalding bath. Shortly after, a neighbour made an anonymous report, which prompted an in-home visit by a public health nurse. The nurse visited the home and made inquiries, but had no choice but to leave without further investigation. She told Gertrude the report was about Sylvia. Gertrude told her that she had kicked Sylvia out of her house, and that her whereabouts were unknown.

Sylvia was often deprived of water and was unable to produce tears due to dehydration.On October 22nd, Sylvia was forced by John to eat a bowl of soup with her fingers. John quickly took away the bowl when Sylvia attempted to eat it. Gertrude eventually allowed her to sleep upstairs, under the condition that she didn’t wet herself. That night, Sylvia asked Jenny to give her a glass of water before falling asleep. On October 23rd, Gertrude discovered that Sylvia had wet herself. As punishment, she was forced to masturbate with an empty glass Coca-Cola bottle in front of Gertrude’s children. After that, she stripped Sylvia naked and carved the words "I'M A PROSTITUTE AND PROUD OF IT" onto Sylvia’s abdomen with a heated needle. When Gertrude couldn’t to finish the branding, she had Richard Hobbs finish it. Richard did what he was told. Meanwhile Gertrude calmly took Jenny to the supermarket. Richard Hobbs and 10-year-old Shirley Baniszewski then used a red hot iron poker to burn the letter "S" into Sylvia’s chest; the burn scar ended up looking like the number "3." Gertrude later teased Sylvia about how she would never be able to marry a man due to the words carved onto her stomach. Sylvia was thrown back into the basement, where Coy Hubbard arrived to tie her up. He then slammed her body against the brick walls seven times. That night, Sylvia told to her sister, "I'm going to die, I can tell". The next day, Gertrude woke Sylvia then dictated a letter to her, intending to make her parents believe that she had ran away. The letter also tried to frame a group of anonymous boys for abusing and mutilating Sylvia after she supposedly agreed to have sex with them. After Sylvia had finished the letter, Gertrude formulated a plan to have John Jr and Jenny take Sylvia to a nearby forested area and leave her there to die. On October 25, Sylvia tried to escape after overhearing Gertrud’s plan to blindfold her and dump her body in Jimmy's Forest. Sylvia fled to the front door but due to her injuries didn’t get very far and Gertrude caught her in time. Sylvia was provided with toast but couldn’t eat it due to dehydration. Gertrude shoved the toast into her mouth and hit her in the face multiple times with a curtain rod. She then violently threw Sylvia into the basement and with the assistance of Coy, she tied and bludgeoned her until she was unconscious. Sylvia managed to recover but was unable to speak intelligibly nor move her limbs properly. Sylvia tried to exit the basement but then collapsed before she could make it to the stairs. Gertrude crushed her head with her feet and stood there for several moments.

On October 26, after multiple beatings, burnings, and scalding baths, Sylvia died. She was 16 years old. When Stephanie Baniszewski and Richard Hobbs realised that Sylvia was not breathing, Stephanie tried to give her mouth-to-mouth resuscitation. Gertrude shouted at them that Sylvia was "faking it”. When Gertrude finally realised that Sylvia was dead, she sent Richard to call the police from a nearby payphone. When police arrived, Gertrude handed them the letter she had forced Sylvia to write a few days previously. Before the police officers left the house, however, Jenny Likens approached them and said, "Get me out of here and I'll tell you everything." Her statement, combined with the discovery of Sylvia’s body, prompted the officers to arrest Gertrude, Paula, Stephanie and John Baniszewski, Richard Hobbs, and Coy Hubbard for murder. Other neighbourhood children present at the time—Mike Monroe, Randy Lepper, Darlene McGuire, Judy Duke, and Anna Siscoe—were also arrested for bodily harm.

An examination and autopsy of Sylvia’s body revealed numerous burns, bruising, muscle and nerve damage. All of her fingernails were also broken backwards and most of the skin's outer layer peeled off. Sylvia had bitten bit through her lips due to pain, partially severing each of them. Her vaginal cavity was nearly swollen shut, although an examination of the canal determined that her hymen was still intact, which meant it was possible she was still a virgin. The official cause of death was brain swelling, internal haemorrhaging of the brain, malnutrition and shock from severe and prolonged damage to her skin. During the highly publicised trial, Gertrude denied being responsible for Sylvia’s death. She pleaded not guilty by reason of insanity. She claimed that she was too distracted by her ill health and depression to control her children.

Four minors who took part in the abuse of Sylvia were also put on trial. They were:

Paula Baniszewski, aged 17

John Baniszewski, aged 13

Richard Hobbs, aged 15

Coy Hubbard, aged 15

The attorneys for the minors claimed that they had been pressured by Gertrude

When Gertrude's 11-year-old daughter, Marie Baniszewski, was called to the stand as a witness for the defence, she broke down and admitted that she had been forced to heat the needle with which Hobbs had carved Sylvia’s ' skin.

On May 19, 1966, Gertrude Baniszewski was convicted of first-degree murder. She was spared the death penalty and was sentenced to life imprisonment.

Paula Baniszewski, who had given birth to a daughter during the trial, was convicted of second-degree murder. She was also sentenced to life imprisonment.

Richard Hobbs, Coy Hubbard, and John Baniszewski Jr. were all convicted of manslaughter and given two 2-to-21-year prison sentences.

Unfortunately Gertrude was granted parole in 1985 due to good behaviour. She later died of Lung cancer in 1990

The house where Sylvia died has since been demolished.

A six-foot-tall (1.8 m) block of granite was dedicated in June 2001 as a memorial to Sylvia in Willard Park, 1700 E. Washington Street.

Sylvia’s case has been the inspiration for numerous films and books.