FITCHBURG, Wis. (AP) – Police are helping the FBI search south-central Wisconsin for a Chicago man wanted in a federal murder investigation.  Authorities began searching for the 33-year-old man Thursday morning in Fitchburg, near Madison.  WISC-TV reports dispatchers describe the man as dangerous. Anyone who spots him is asked to call 911.   The Wisconsin State Journal reported the Verona School District high school was locked down as of 1:30 p.m., with classroom doors locked and students told to stay down. Two elementary schools in the Madison district were on soft lockdown, with exterior doors locked. Neither district immediately returned phone calls from The Associated Press.  The suspect is described as a black man, 30 to 35 years old, 6 feet tall, 200 pounds, with dreadlocks.