A long time ago - late 1940s/early 1950s, several members of the Italian mafia lived in River Forest and Elmwood Park.
Some kids from the Austin neighborhood made the mistake of robbing a woman in River Forest. Certain people found those kids, beat them to death, and hung their bodies from lamp posts in the Austin neighborhood.
A couple of decades later in the 1980s, some hood rats invaded a BBQ in a River Forest backyard. 20 minutes later, the invaders were shot dead in their cars by River Forest police.
Those actions paid dividends well into the 1990s, where River Forest remained relatively safe while its liberal neighbor Oak Park became increasingly dangerous.
The only thing that feral behavior responds to is ferocity.