Walter Earl Ellis was born on June 24, 1960, in Holmes County, Mississippi, and later moved with his family to Milwaukee, Wisconsin. Growing up in Milwaukee's North Side, Ellis exhibited antisocial behavior from an early age, often acting aggressively towards peers. He dropped out of school in the 8th grade and turned to a life of crime, accumulating a lengthy criminal record that included robbery, assault, and drug offenses. Despite multiple arrests and incarcerations, Ellis managed to avoid significant prison time for many of his offenses.

Between 1986 and 2007, Walter Ellis targeted vulnerable women in Milwaukee's North Side, many of whom were involved in sex work or struggled with addiction. His modus operandi involved luring victims to secluded areas, sexually assaulting them, and then strangling them to death. The bodies were often left in alleys, abandoned buildings, or other isolated locations.

For years, these murders were treated as isolated incidents. It wasn't until May 2009 that DNA profiling linked the cases together, revealing a pattern of serial killings. Investigators discovered that Ellis had previously avoided providing a DNA sample by convincing a fellow inmate to submit a sample on his behalf. This deception delayed his identification as the perpetrator.

On September 7, 2009, Ellis was arrested at a motel in Franklin, Wisconsin. DNA evidence from a toothbrush found in his residence matched samples from multiple crime scenes. In February 2011, Ellis pleaded no contest to seven counts of first-degree intentional homicide and was sentenced to seven consecutive life terms without the possibility of parole.

Ellis died on December 1, 2013, from complications related to diabetes while incarcerated at the South Dakota State Penitentiary. His death marked the end of a decades-long investigation and brought a measure of closure to the families of his victims.