Adrie "Aalt" Mondria was born on May 9, 1956, in Kampen, a town in the Dutch province of Overijssel. He grew up in a small community called Vollenhove. As a child, not much is known about his early life. However, it seems that he faced challenges as he grew up.

During his teenage years, Mondria entered a troubled phase. He began his criminal activities when he was a teenager. His first conviction came in 1976 when he was caught threatening another criminal. He was sentenced to four months in a treatment clinic. While in the clinic, he struggled to control his behavior. He often broke things and caused problems, which made him difficult to manage. Eventually, he escaped from the clinic.

In 1978, Adrie "Aalt" Mondria escaped from a treatment clinic. He went into hiding at his girlfriend's apartment in Amsterdam. There, he and his girlfriend assaulted the landlady, leaving her permanently paralyzed. After this incident, they fled to North Brabant.

On July 30, 1978, Mondria and his girlfriend entered a house in Hoeven. Inside, they murdered an elderly couple and their 38-year-old daughter. The motive for this crime was robbery, with the stolen items valued at less than 10 guilders. Mondria was sentenced to 15 years in prison for this triple murder. Due to his mental health issues, he was later transferred to the Van Mesdag Clinic in Groningen, where his behavior continued to be violent. He took a social worker hostage twice while in the clinic.

In 1998, Mondria was granted trial leave. During this leave, he was arrested again for shooting three men in a café in Zwolle after a fight.

In 1995, Mondria placed a personal advertisement and began a relationship with a 30-year-old woman while still in the clinic. In 1996, he was allowed to live with her and her 10-year-old son in Groningen. When the probation service instructed him to return to the clinic, he forced them to flee with him. On March 6, 1997, he murdered the boy in Zwolle. His girlfriend reported the crime to the police the next day. Mondria surrendered to authorities and initially confessed but later retracted his statement.

On September 11, 1997, Mondria was sentenced to life imprisonment. However, during an appeal in June 1998, his charge was changed from murder to manslaughter, and his sentence was reduced to 18 years. Throughout his legal process, Mondria claimed that he was a victim of conspiracy. In January 2003, a lawsuit regarding the extension of his imprisonment found that his aggression mainly appeared in isolation. He was described as suffering from serious delusions.

In 2001, Mondria displayed his body in court, claiming it had holes from injections. Experts at the Veldzicht clinic noted that he was likely untreatable, making his release improbable. His sentence was extended again in February 2007.

On September 28, 2011, it was reported that Mondria had passed away during the summer due to untreated Hepatitis C.