Kansas City, Mo. ? A former supervisor for a trash-collection company was charged Thursday in a 13th killing.

Lorenzo J. Gilyard, 55, was charged with first-degree murder for the death of Helga Kruger, an Austrian national who was killed in February 1989.

“This is a pretty sad and somber milestone for us in that Lorenzo Gilyard, at 12 victims, was already the most prolific serial killer this region has ever seen,” Jackson County prosecutor Michael Sanders said during a news conference.

“Now we can add, we allege, a 13th victim to that milestone or marker.”

Gilyard already was charged with strangling a dozen women ranging in age from 15 to 36 – all but one a prostitute – between 1977 and 1993. He was arrested in April 2004 after the crime lab used money from a federal grant to begin DNA testing of evidence in the city’s cold-case files.

Sanders said the Kruger case would be tried separately to avoid slowing down the prosecution of the other 12 cases. Prosecutors plan to seek the death penalty in those cases.

Calls to the capital division of the Missouri State Public Defender’s Office, which is now handling the case, were not immediately returned. No court date has been set for Gilyard to appear on the latest charge, said Kelley Carpenter, a court spokeswoman.

The crime lab linked DNA from Kruger, who was 26 when she was found nude and lying facedown in the street, to Gilyard in February.

Sanders would not discuss whether Kruger was a prostitute, but Kansas City Municipal Court records show she was convicted of solicitation in 1988 and 1989.

Kruger was found with a paper towel in her mouth, ligature marks around her neck and extensive bruising and abrasions to her body, according to a probable cause statement. A medical examiner ruled the cause of death to be asphyxiation.

Kruger moved to the Miami area from Innsbruck, Austria, in the mid-1980s and to Kansas City in 1987, Sanders said. Since the crime lab made the connection to Gilyard earlier this year, detectives have been unable to find anybody who knew her. And prosecutors offered few details about her past.

At the time he was charged with the killings, Gilyard was married and described by some neighbors as mild-mannered and friendly. But the suspect had a long history of scrapes with the law, and police had taken a blood sample from him in 1987.