The Cook County Jail isn't just a storehouse of accused felons. To investigators, it's also a veritable vault of information.
The largest facility of its kind in the United States, and home to more than 9,000 gang members, the facility is a valuable starting point for officers with the sheriff's Criminal Intelligence Unit, who make it their business to learn as much as they can from the inmates.
Each day, hundreds of new inmates are processed into to the jail, and every day CIU investigators walk among them, asking questions, trolling for targets who may be willing to talk about open cases or trouble which might be brewing inside.
"They're looking to make their stay here a little bit easier. They're thinking, 'This is what I have to do? What's in it for me?'" said CIU Supt. Frank Diaz.
That back and forth is so compelling that Diaz's unit and the jail are the subjects of an upcoming MSNBC series called "The Squeeze."
In the series, police show how even graffiti and gang signs on the streets can provide information about what is happening and what is about to happen.
"If you look at them, they all have their own little insignias, and they're all telling a story," said CIU Director Thomas Kinsella.
Since January of last year, the sheriff's police say CIU investigators working sources have helped solve 20 murders and over 150 cases.
And authorities say their information highway works both ways. Investigators can take information gleaned from crime scenes back to the jail and try to squeeze more information from inmates, asking them if certain details are pertinent to a case or if a different lead should be followed.
"This is what they train for. You know, they are very good at what they do," said Gang Intelligence Unit officer Jason O'Malley.
Investigators say an inmate who wants something as simple as his visiting days adjusted will sometimes contact them wanting to cooperate.
"Come at me in a truthful manner, and we'll move forward from there," Diaz said. "If not, all I have to do is move on to the next inmate.
"The Squeeze" premieres Friday at 9 p.m.