Robert Wirth

Case record: Robert Wirth

Background

Robert Wirth murdered elderly women in their homes. The killings were occurring about every week and involved burglaries in the areas of the homicides. The burglaries had an almost exactly similar type of entry and similar disheveling of the home.

The offence

The case involved three women who were murdered in their homes. The victims had neck injuries, including external neck injuries in one of the victims. The victims died of asphyxiation. One victim sustained a complete avulsion of the voice box, and the medical examiners described the injuries in all three victims as unique, with internal and external injuries that were consistent.

Investigation

Powerful medical examiner testimony was presented. Three medical examiners examined the autopsy protocols and opined that one person was responsible for all three homicides based on the injuries and their extent.

At one of the homicide scenes, a detective observed a toy donkey sitting on the couch. A family member stated that the toy donkey did not belong there. The toy donkey actually belonged on a chair right where the body of one of the victims was found. When the detective picked up the toy donkey and turned it over, the detective observed very fresh blood smears on the toy donkey.

The toy donkey was taken immediately to the Wisconsin State Crime Laboratory to check whether the blood on the donkey was foreign to the victim. The blood on the toy donkey was foreign blood. The investigators were excited about the fact that they had foreign blood and, since it was fresh, they believed it was likely the assailant. They concluded that if they could find the assailant and perform enough genetic workup for one of the victims, they could obtain a conviction for all of the homicides by combining the medical examiner testimony with genetic evidence.

Arrest

Robert Wirth was caught after he robbed a taxicab driver. The taxicab driver got into a fight with him, and Robert Wirth had a gun. The taxicab driver fought and got the gun away from him. When police ran a check on the gun, they found that the gun was stolen from a residence next door to one of the victims.

After a John Doe proceeding, the authorities obtained permission to get Robert Wirth’s blood, and they took it immediately to the crime laboratory. Robert Wirth’s blood matched the blood on the toy donkey.

Trial

The case went to trial. It was a lengthy trial and involved a six-week sequestered jury trial. The jury convicted Robert Wirth largely because of the DNA evidence.

The presentation included genetic workup using markers and probability figures. Before the advent of DNA, the investigators used ABO enzyme markers, with probabilities described as “1 in 500” and “1 in 600.” The investigators described that if they had “1 in 1,000,” they considered it a terrific case and believed it was wonderful evidence. They also referenced that the case involved one marker, four RFLP markers, one PCR marker, and the most conservative number was “1 in 800,000.” The investigators described additional testing as including Ed Blake in California and work conducted at Sonar Diagnostics, along with testing at the Memorial Blood Center in Minneapolis, using gamma markers and cappa markers.

Robert Wirth matched the blood on the toy donkey with the PCR marker available at the time, and investigators described additional testing and combinations of genetic markers. They described that they felt that with a probability of “1 in 800,000” they could find the combination of all genetic markers.

Sentencing

Robert Wirth received four consecutive life terms plus 20 years in prison in 1991.

Outcome

Robert Wirth was convicted and sentenced to four consecutive life terms plus 20 years in prison in 1991.