Impeachable offense, when it made a difference.
One commonly-used, ridiculously easy MO:
A crooked govt insider in collusion w/ govt factotums creates phony invoices (supposedly submitted by "contractors" for work that never existed).
The govt agency then writes the check to pay the bill out of govt funds set aside for contractual work.
But the check is deposited in a secret LLC account, accessible only by the crooked insider.
Billions can be stolen in this easy-peasy, no-sweat manner.