There was an expose on Michael Posner after the Natalee Holloway incident in 2006.
http://abclocal.go.com/wls/story?section=news&id=3936339The article lists Posner as in charge of gambling and prostitution in Lake County. It appears he has a 1987 conviction for gambling, extortion, and the usual. According to the federal BOP website, he was released in 1992.
http://articles.chicagotribune.com/1987-...l-investigatorsThe above article mentions that Posner belonged to Ferriola in Cicero.
The first article claims that he has run the casino since 1998. Wikipedia lists Posner as also running two other Aruban casinos. If true, this would be around the time that Elmwood Park retreated.
This is pure speculation, but perhaps in exchange for ceding control of street rackets to the Southside crews, Elmwood picked up the casinos. If I had to guess, I would say 99% of what occurs at the Excelsior is legal. It's a cash cow for DiFronzo and his pals.
If you look at other articles related to Posner, it seems that his relative, likely a brother or nephew since he has no kids, is also running the show.