William James Bosket Jr. was born on December 9, 1962, in Harlem, New York City. His father, Willie Sr., also known as Butch, committed a double murder in 1962 shortly after Bosket was conceived. Butch was sentenced to life in prison for those crimes. While incarcerated, he earned degrees in computer science and psychology. After serving his time, he got a job as a computer programmer at an aerospace company. However, he faced legal trouble again when he shot his girlfriend and took his own life to escape arrest.

Bosket's early life was filled with trauma. His grandfather, who had also been in prison, abused him when he was young. When Bosket was only nine years old, he had to defend his mother, Laura, from her abusive boyfriends. He showed signs of aggression and violence, even attacking one man with a pipe and threatening another with fire. In addition to these challenges, Bosket suffered a serious head injury when he was struck by a car.

At the age of nine, Bosket’s mother sought help for him, describing him as "a person in need of supervision." Initially, he was placed in The Children's Center in Manhattan but escaped shortly after. He was then moved to Spofford, a secure detention center similar to an adult prison. Throughout his childhood, he frequently moved in and out of different detention centers and reformatories. His mother advised him to stand up for himself, telling him to hit back and be tough.

On March 19, 1978, William James Bosket Jr., who was fifteen years old at the time, shot and killed Noel Perez. This took place on the New York City Subway's 3 train during an attempted robbery near the Harlem–148th Street terminal. Eight days later, Bosket and another accomplice shot and killed Moises Perez, who was not related to the first victim, on another 3 train at the 145th Street station. In the days between these two murders, Bosket and his accomplice also shot a New York City Transit employee and committed two more armed robberies.

Bosket was put on trial for the murders in New York City's family court. During the trial, he unexpectedly pled guilty to both murders. The court sentenced him to a maximum of five years in the Goshen Youth Facility. Although the prosecutors wanted a longer sentence, five years was the maximum allowed under the law at that time.

The short sentence caused a public outcry, which led to changes in New York's laws regarding juvenile crime. Governor Hugh Carey called the state legislature to pass the Juvenile Offender Act of 1978. This new law allowed children as young as thirteen to be tried as adults for serious crimes like murder.

A year after starting his sentence, Bosket escaped from the youth facility. He was caught two hours later and was tried as an adult for the escape. He received a four-year prison sentence. He was eventually returned to the Division of Youth, but after being released in 1983, he was arrested again just 100 days later. He was charged with robbery and assault against a neighbor. While waiting for trial, he assaulted court officers and was found guilty of attempted assault, receiving a seven-year prison sentence.

At this time, Bosket was now sixteen, which meant he was classified as an adult for criminal offenses. Escaping from a youth facility is a felony in New York. If convicted of assaulting the court officers, he would have faced a serious sentence. But he was acquitted.

Feeling that he would spend the rest of his life in prison, Bosket began to act violently against correction officers. He got into many fights and was ultimately convicted of assault and arson, receiving a 25-years-to-life sentence. In 1989, while incarcerated, he stabbed a corrections officer and was given another 25-years-to-life sentence. After the stabbing, he was moved to Woodbourne Correctional Facility, where he assaulted another officer and got a third consecutive 25-years-to-life sentence.

Now serving a total of 82 years to life, Bosket has spent a significant amount of his life in solitary confinement. His living conditions include being watched by video cameras, with restrictions on his activities outside his cell. He has faced many disciplinary issues in the past, but there have been no reports of violations since 1994.

Over the years, Bosket has been moved between several maximum-security facilities, and by December 2022, he was housed at Wende Correctional Facility. His life in prison has shown a pattern of violence and incidents, but recent evaluations suggest he may be considered for a move to the general population sooner than initially planned.