Josh Marks 911 Call -- 'There's a Dead Body In the Alley'

The woman who called 911 to report the death of "MasterChef" contestant Josh Marks was extremely calm -- considering she just learned there was a dead body in the alley.

TMZ obtained a recording of the 911 call placed after Marks shot himself in an alley in Chicago on October 11.

The woman who calls for help says ANOTHER woman had just rang her doorbell and informed her that she had just discovered a dead body, but she was too afraid to call police.

But the caller, with nerves of steel, calmly explains the situation to the 911 dispatcher -- who sends responders to the scene.

When cops arrived ... they discovered the body was the 7'2" chef -- who shot himself in the head after learning he was suffering from schizophrenia.

Marks was 26.