http://www.tmz.com/2010/03/19/corey-haim-coroner-cause-of-death-drugs-heart-respiratory-pneumonia/
From TMZ;
Although final autopsy results won’t be released until tomorrow, TMZ is reporting that troubled former teen star Corey Haim actually died of natural causes, rather than drugs. The preliminary report reportedly states that heart problems, coupled with pneumonia, led to the untimely death.