A Sun-Times analysis shows that since the mid-1990s, 18 different engineering and construction companies have made more than $3.6 million in campaign contributions -- $1.3 million of which went to Rod Blagojevich.
Eleven of those firms were awarded $656 million in state contracts.
Now federal investigators are looking at those companies as part of their "pay-to-play" probe of Blagojevich.
