There has never been an case of death reported from using marijuana. You would fall asleep from ingesting too much pot before it would kill you. There may be some cases where synthetic or altered marijuana caused the death of a person. However, this substance was not what is commonly considered to be marijuana.
There is not one single report showing that marijuana has been directly the cause of some one's death. The greatest risk with marijuana found so far, out of all the testing completed, is that if a person were to over dose on marijuana they would pass out and sleep for a while. That doesn't sound too deadly to me, especially when it's compared to what happens if a person over doses on other substances including alcohol. Marijuana has many healing properties and can be good for the body when taken in ways other than smoke. The rumor of it causing death was creating many years ago to abolish it, there is no truth to it what so ever.