CRIME, did you lose a pipe bomb in Oak Park?

Wednesday Journal (Bill Dwyer):

A functional pipe bomb found lying on a snow bank in South Oak Park was defused by the Cook County Bomb squad Tuesday afternoon. Experts described the bomb as functional and "well made."

The bomb was spotted on a pile of snow in a parkway by a man walking in the 1150 block of Lyman Avenue around 3:30 Tuesday afternoon. He immediately called 911, and responding Oak Park police, after a cursory examination, called in the county's bomb and arson squad stationed at the Maybrook complex in Maywood.

How would a "well made" pipe bomb end up in an Oak Park snow bank?