A man of many criminal hats, Kyle Knight, took the stand late Tuesday afternoon in the racketeering trial of Michael Sarno.

Knight, a career thief and former drug user, will be a key witness for the government as he describes how he and another government informant, Mark Hay, robbed jewelry stores and brought their stolen diamonds to Mark Polchan, who owned a pawnshop in Cicero and is a codefendant in the case.

Knight pleaded guilty in September 2008 to providing the powder that was used in making a bomb that gutted a business in Berwyn that was competing with a mobbed-up video poker company. Knight also admitted to robbing a variety of jewelry stores. His plea agreement calls for a serious reduction in his prison sentence in exchange for helping the government.

Prosecutors are also using Knight to show the men on trial along with Sarno knew one another and worked together. This is being done to help them prove the racketeering conspiracy charge against four of the five defendants.

Like many star witnesses in government mob cases, Knight has his problems. He has a history of using cocaine and crystal meth. He has committed so many home burglaries that he lost count. He has an unusual speaking voice on the witness stand that is, at times, reminiscent of the Dustin Hoffman character from the film, "Rain Man."

Defense attorneys will certainly pounce on his criminal background and likely question his memory given his drug use. Prosecutors, in turn, may point out that Knight is the guy who many of the defendants on trial chose to hang out with. Prosecutors, in short, didn't pick him; the defendants did.

Knight's direct testimony will continue 9:30 a.m. Thursday in federal court in Chicago. For all the trial buffs who have written in to the blog, wondering when the good testimony will happen, this should be interesting for much of the day.