[layman]

Two guns that were sold during Operation Fast and Furious were found at the scene of the murder.

Ever since this story broke the thing that has puzzled me is why would the murderers leave the murder weapon at the scene of the crime? Is this customary in Mexico?

[Ben Hecks]

Ever since this story broke the thing that has puzzled me is why would the murderers leave the murder weapon at the scene of the crime?

The guns are expendable. If left at the scene, it can't be traced to the shooter. The shooter just gets a new gun.