CHICAGO (CBS) — Cook County is demolishing three divisions, representing close to a half-million square feet of cell space, as the jail population has hit the lowest level in 25 years.

Cook County officials stood in a muddy yard behind the razor wire and walls at the jail complex as demolition started on the first building. WBBM’s Mike Krauser reports.

“Jails are for violent people,” said Sheriff Tom Dart, “and we have a lot of violence in our society.”

“We are always going to have places for them here,” Dart said. “But for the non-violent people, for the mentally ill, they don’t need to be here and through a lot of the work we’ve been doing for the last few years we have been able to get a lot of those people out of here.”

County Board President Toni Preckwinkle said a lot of progress has been made in what she sees as ‘righting the wrongs’ of the criminal justice system in Cook County.

“We know that holding people in jail destroys lives. Even a short period of pre-trial detention can result in the loss of your job or your home,” Preckwinkle said. “Every effort needs to be made to be sure that people can keep working, attending school and caring for their families as they await trials.”

She said demolishing the old buildings, some dating to the 1920s, will save $3-million in the short-term and $188-million over the next decade that won’t have to be spent on up-keep.

The jail’s capacity will go from 11,300 to about 9,600.