[Johnny Wadd]

Walter E. Ellis, the serial killer serving several life sentences for the slayings of seven Milwaukee women over two decades, died Sunday.

Ellis, 53, was incarcerated at a South Dakota prison under an interstate agreement. He died of apparent natural causes at a Sioux Falls, S.D., hospital, according to a South Dakota prison official.

An autopsy will be conducted.

Ellis was arrested in 2009 after Milwaukee police said his DNA matched semen samples found on six homicide victims and a blood sample on a can of pepper spray discovered at the scene of the seventh slaying. The homicides occurred between 1986 and 2007. All seven victims were strangled. One also was stabbed.

His case exposed serious flaws in Wisconsin's process for collecting DNA from convicted felons. Ellis' DNA was missing from a state database even though he should have submitted a sample while serving time for beating a girlfriend with a hammer. Authorities said Ellis persuaded a fellow inmate to submit a DNA sample in his place.

Police later said that if a sample had been taken from Ellis at that time, they may have been able to track him down before the last slaying, in 2007.

Two men were convicted and later exonerated in slayings later linked to Ellis.

William Avery was convicted wrongfully in the 1998 slaying of Maryetta Griffin. Avery maintained his innocence but was convicted in 2005 and served six years before he was released when DNA tests were done on evidence recovered from the crime scene, which matched Ellis, who was later convicted of killing Griffin.

Another man, Chaunte Ott was convicted in 1996 for the murder of Jessica Payne, a 16-year-old South Milwaukee runaway. He served 13 years of a life sentence before he was freed, after his lawyers showed that DNA found on Payne matched that on two other women later determined to be Ellis' victims. Ellis was not charged in Payne's homicide.

In a third case later linked to Ellis, Curtis McCoy was charged and tried but acquitted in the 1994 murder of Carron D. Kilpatrick.

Ellis never explained why he killed seven women over 21 years. At his sentencing in February 2011 he remained silent after unexpectedly pleading no contest to seven counts of first-degree intentional homicide. He was sentenced to seven consecutive life terms.

Investigators arrested Ellis in 2009 after advances in technology linked DNA from several unsolved prostitute murders. Ellis emerged among a small group of suspects. Police got a sample of his DNA from a toothbrush, which matched evidence at the murder scenes, and he was arrested at a Franklin motel just 16 weeks after a task force was formed.

The South Dakota Division of Criminal Investigation is investigating Ellis' death, which is standard procedure in the death of an inmate.

He got off lucky after only serving 4 years

[Photoplay]

Wow! Two innocent men were arrested
Hadn’t heard of Walter E. Ellis before.

[Pyramid_Head]

This wouldn't have happened had they just executed him when he was found guilty.

[Megamel29]

"Ellis was not charged in Payne's homicide."

Why not?