Kile apparently died from natural causes and was found in his bed, said Michael Chasen, commanding officer of the Chicago Police's Area Three Homicide.
Kile, who was 16-11 with a 3.09 ERA and threw 227 1/3 innings last year, had arthroscopic surgery on his right shoulder during the offseason.
Kile was traded to St. Louis from Colorado, along with pitchers Dave Veres and Luther Hackman on Nov. 16, 1999, for pitchers Jose Jimenez, Manny Aybar and Rick Croushore and infielder Brent Butler.
Kile, 33, was found dead at the team hotel Saturday, hours before his St.
Kile was 8-13 with a 6.61 ERA for the Rockies in 1999, and 20-9 with a 3.91 ERA for St. Louis in 2000, finishing fifth in the NL Cy Young balloting.
Kile was such a perfect soldier for manager Tony La Russa that he stood in for nervous rookie Rick Ankiel one day before an NL playoff game in 2000, rattling off his usual patter of non-answers so that some reporters didn't even notice he never confirmed he was not the actual starter of the game.