I really like the way they "sell" it as non-violent .... a non-violent drug dealer petals a product that "kills" - overdose, altercations, robbery, etc by the user. Many of these non-violent criminals actually are violence producers - enablers. I also see where some had "gun" charges along...
Send him a certified letter, signature required, detailing the events and include a demand for a refund or product within 10 days of receipt. Inform him that your next step will be small claims court and since a USPS money order was used, notification of Postal Inspection Service for fraud...