Simon Monjack -- Cause of Death Still a Mystery

6/2/2010 7:00 PM PDT BY TMZ STAFF
We just obtained the death certificate of Brittany Murphy's husband, Simon Monjack ... and the cause of death has not been determined.


According to the document, the cause of death is "deferred."  The certificate lists Monjack as "film maker" ... in "entertainment."  It also notes his marital status -- "widowed."

The death certificate lists Monjack as 40 years old.