Milwaukee police say DNA evidence has linked a seventh slaying to a serial killer who has been active in the area for more than two decades.

Police Chief Ed Flynn and the Milwaukee County District Attorney John Chisholm announced Monday that officials used DNA evidence to tie the deaths of six women — five of them prostitutes — to one person.

On Tuesday, police said they had linked another dead prostitute to the killer.

The victims were killed between 1986 and 2007 on Milwaukee's north side.

The one victim not connected to prostitution was involved in drug use and sales.

Police have submitted or resubmitted DNA samples from more than two dozen unsolved homicides to see if they are related.

The person known only by DNA killed the six prostitutes over two decades in Milwaukee, the city where serial killer Jeffrey Dahmer once cruised gay bars for victims, police said.

The killer's DNA was also found on the body of a 16-year-old female drug abuser slain in 1995.

Milwaukee police spokeswoman Anne E. Schwartz said police believe the man suspected in the six other slayings had sex with the 16-year-old and didn't kill her but knows who did.

More than 20 DNA samples from other unsolved homicides of prostitutes are being re-sent to the state crime laboratory to check for possible links to the killer, Flynn said.

Flynn said the unknown killer has never been arrested for a felony, which is Wisconsin's basis for those who must submit to DNA testing.

"He does not appear in any DNA database" checked by investigators, the chief said.

Flynn also said DNA tests showed the Milwaukee cases were not linked to murders of prostitutes that are part of active investigations in Los Angeles, Las Vegas and Mesa, Ariz.

Anyone working as a prostitute is in an "extraordinarily vulnerable population," Flynn said.

Chisholm said improved technology makes it more likely the killer can be found. "We're convinced we're going to be able to bring justice to these victims and their families," Chisholm said.

Dahmer admitted killing 17 men and boys between 1978 and his arrest in 1991 at his Milwaukee apartment where parts of some of his victims were found.

He was serving multiple life terms when a fellow prison inmate beat him to death in 1994.