1) Conclusive evidence 2) Damning evidence 3) Indisputable evidence 4) Irrefutable evidence 5) Proof positive 6) Strong proof 7) Tobacco-using paladin 8) Whodunit evidence 
The term `smoking gun` was originally, and is still primarily, a reference to an object or fact that serves as conclusive evidence of a crime or similar act. In addition to this, its meaning has evolved in uses completely unrelated to criminal activity: for example, scientific evidence that is highly suggestive in favor of a particular hypothesi.....
Slang for evidence that decisively proves a cause.
noun indisputable evidence (especially of a crime)