Compare and Contrast Substantive Law and Procedural Law

For this discussion board, please review the hypothetical and answer the following questions:

Paul, a law enforcement officer, arrests Barney for creating a disturbance at a subway station. While Barney is handcuffed face down on the ground, Paul shoots and kills him. Paul claims that he accidentally grabbed his gun instead of his Taser.

1. How do you define substantive criminal law?
2. How do you define criminal procedure?
3. What questions of analysis should you ask when deciding whether this was an issue of substantive law or procedural law? (i.e. Did the Defendant commit a crime? Assuming the defendant would be Paul in this case, the alleged crime would be murder.)
4. Is this an issue of substantive criminal law or criminal procedure and why?