Ellis had been in trouble with the law before. He pleaded no contest in 1998 to a reduced charge of second-degree reckless injury and served three years of a five-year sentence, police Chief Edward Flynn said. That wasn't enough to raise red flags, Flynn added, and it was only in recent years that DNA technology evolved enough to connect the cases to the suspect, the chief said.
"Yes, he does have a criminal history," Flynn said. "His criminal history, however, does not lend one to immediately say, you know, 'prime suspect.'"
Police began to focus on Ellis after his name surfaced in connection with a number of unsolved homicides, Flynn said. The chief would not be more specific.
Ellis was arrested days after police matched a DNA sample from his toothbrush to samples from the victims.
A warrant for him was issued Friday, and on Saturday an officer in suburban Franklin saw Ellis' car. Ellis was arrested after struggling with officers, Flynn said.
Milwaukee County District Attorney John Chisholm did not know whether Ellis had an attorney. A message left with Ellis' previous attorney was not returned Monday.
Police said Ellis' DNA was found on the bodies of nine women, ranging in age from 16 to 41. They were killed between 1986 and 2007 on the city's north side. Investigators believe eight of the women were prostitutes and one was a runaway.
Authorities previously have speculated that the person whose DNA they recovered on the runaway had sex with that girl but that someone else killed her. But Chisholm would not say Monday whether anyone else would be charged in the killings.
Flynn and Chisholm announced the arrest and charges at a brief news conference and left a number of other questions unanswered. Flynn wouldn't speculate on a motive, characterize Ellis' childhood or describe a possible relationship to the victims.
"I don't think it's possible for me to speculate what would cause someone to engage in these horrific acts," Flynn said.
Ellis is charged with two counts of first-degree intentional homicide, charges that carry a maximum penalty of life in prison. Additional charges will be filed after prosecutors have a chance to review more evidence, Chisholm said.
One victim was Joyce Mims, who was strangled in 1997 at the age of 41. On Monday, her brother said his family has carried a great burden since Mims' death.
"We just hated that it had taken so long for them to find her killer, those women's killer," said Terry Williams, 49, of Madison. "But you know, justice one day is better than no justice at all."
The overall investigation produced breaks in other unsolved cases after detectives resubmitted numerous DNA samples to the state crime lab. The work led to progress in at least 10 unrelated killings, authorities said.
"This is a phenomenal feat," Mayor Tom Barrett said. "The lesson here is there is never a totally cold case in the city of Milwaukee."