CHICAGO — Detectives have long wondered what secrets serial killer John Wayne Gacy and other condemned murderers took to the grave when they were executed — mostly whether they had other unknown victims.

Now, in a game of scientific catch-up, the Cook County Sheriff's Department is trying to be creative: They've created DNA profiles of Gacy and others and figured out they could get the executed men entered in a national database shared with other law enforcement agencies because the murderers were technically listed as homicide victims when they were put to death by the state.

The department's hope is to find matches of DNA evidence from blood, semen or strands of hair, or skin under the fingernails of victims that link the long-dead killers to the coldest of cold cases. And they're hoping to prompt authorities in other states to submit the DNA of their own executed inmates or from decades-old crime scenes.