From www.comicbookresources.com

This is some sad news. Mike Wieringo was an incredible artist. Currently his web site is down (at about 3:30 central) but when you do get a chance look through his sketches and his “How-To” articles.

The comics industry has lost one of its most respected members this weekend – artist Mike Wieringo has passed away at the age of 44, according to numerous sources speaking with CBR News. Details are unclear right now, but early reports say he experienced a sudden and massive heart. Newsarama is reporting that Sunday afternoon Wieringo experienced chest pains and did call 911, but first responders were unable to reach him in time.

You can see more of his work on Deviantart as well