So, so very sad to have heard this last night and no one seems to know what happened. I was with several people who knew him well and learned the news via a Facebook post. The age of social media.
My first memory of seeing him on stage was Chicago on Broadway in 2004. From "All That Jazz" to curtain call, I honestly am not sure if I even bothered to watch anyone else.
I had the pleasure of meeting and working with Greg on several occasions. He was an alumni of the school I did my undergrad degree at and he was such a supporter of young artists. More then once he helped guide me down the right career path, whether he realized it or not.
He spent the last few years working as a faculty member at Michigan State and his students loved him. He was a tremendous asset to the Midwestern theater community and he will be missed greatly.
A close friend posted on his Facebook that they are awaiting the autopsy results, but no foul play or suicide is suspected. May have been related to a health issue.