Law enforcement cracking down on those threatening judges

Law enforcement officials in Chicago are cracking down on people who could pose a threat to judges, prosecutors and other public officials.

Since last March, the Cook County Sheriff's police has charged six people and launched investigations of five others.

The U.S. Marshals Service hired a full-time investigator last year to track threats and in October arrested a man for allegedly sending a threatening letter to U.S. District Court Judge Joan Lefkow after identifying the man by DNA left on the envelope.

In 2005, a man whose lawsuits had been dismissed by Lefkow killed Lefkow's mother and husband at her Chicago home.

Cook County Sheriff Tom Dart says his office has been maintaining a data base of people who might be a threat to public officials.