Robert Lee Walden Jr. was born on November 15, 1966, in Chicago, Illinois. He was the second of four children in his family. Walden's early life was troubled. His father struggled with alcoholism and often changed jobs. During his drunken episodes, he would belittle Robert and his siblings. These issues created a difficult home environment for Walden while growing up.

Despite these challenges, his family was seen as respectable in their community. The Waldens encouraged their children to do well in school and participate in sports. Walden claimed he excelled in school activities and sports. He asserted that he was involved in the student council and studied German. He also claimed that he was offered a baseball scholarship, although he could not accept it due to a knee injury.

In 1985, Walden graduated from college and joined the United States Air Force. During his time in the military, he was noted for his heavy drinking. The following year, he was discharged after writing bad checks. After leaving the Air Force, Walden moved to Tucson, Arizona. There, he met Catherine "Cathy" Mills, a 16-year-old single mother. Despite her mother's disapproval, they married.

Once married, Walden's behavior changed. He began to verbally and physically abuse Cathy. He was known to have beaten her, even when she was pregnant with their child. Reports also indicated that he forced her into unwanted sexual acts, causing her humiliation. This behavior marked a troubling shift in his life after his early years.

In 1989, Robert Lee Walden Jr. started a series of violent crimes in Tucson, Arizona. He was charged with attacking two women that year. Instead of serving prison time, he was sent to a boot camp at Florence State Prison. However, he was kicked out for stealing candy from other inmates just before completing the program. A judge decided to place him on intensive probation, which allowed him to work as an exterminator. This job gave him the freedom to move around the city without supervision.

Shortly after Walden's release, a number of rapes occurred in Tucson. The victims were often attacked randomly in apartment complexes. On August 9, 1989, he abducted a woman near her apartment, raped her, and stole her car. On December 22, 1990, Walden killed 31-year-old Nola Jean Knight after raping and severely beating her. Her body was discovered behind a store.

On May 4, 1991, Walden attacked another woman at an apartment complex, stabbing her in the back and then raping her. A few weeks later, on May 15, he posed as a plumber to gain entry into another woman's home. Once inside, he attacked her, binding and gagging her before raping her.

On June 13, 1991, Walden visited the apartment of another victim, Miguela "Lida" Burhans. He attacked her, hitting her with a lamp and attempting to strangle her. After she fought back, he fatally cut her throat.

Police linked Walden to these crimes through fingerprint evidence. In June 1991, after several tips led them to him, he was arrested. While in jail, authorities connected him to more crimes, including the murder of Denene Brevaire-Domet, who he had previously confessed to killing.

Walden stood trial for the rapes and murders. Prosecutors portrayed him as a manipulative psychopath who enjoyed tormenting his victims. Despite his defense claiming he was just a scapegoat, he was found guilty on multiple counts, including murder. He received the death penalty for Burhans' murder and several life sentences for the other crimes.

As of February 2022, Walden remains on death row in Arizona. He has filed multiple appeals against his sentence, but they have been rejected. His crimes and trial were also featured in a documentary series, which included an interview with his wife reflecting on their life together before his arrest.