"You just put it a shipping label on it, a box, they drop it in the UPS, FedEx, whatever carrier might be there and off it goes."
Lt Wildblood says the sticker with computer code on one of the marijuana packages looks like an inventory control sticker from one of California's legal marijuana sellers.
The train did come from California. Wildblood says powerful, high-grade marijuana that may have been grown for California's legal marijuana markets gets diverted into illegal markets.
He says high grade marijuana at 800 dollars a pound in California may sell for 2700 to 3000 dollars a pound in Arizona.
"You get it further back east the price even starts to double on that."
A recent case in New Jersey fits that pattern. A man there just pleaded guilty to getting California marijuana mailed to him in New Jersey. He bribed postal workers to deliver the packages to a fake address.
He got away with the scheme for two years because drug traffickers know there's a good chance their drugs will get through, with thousands of legitimate packages for camouflage.
Shipping companies can and do intercept drug shipments.
Some of the strongest statistics come from the U.S. Postal Service. It says in 2015 it found 34 thousand pounds of marijuana in the mail.
The Postal Service says the amount of opioids it finds in the mail is up 880 percent.