An investigation that began with a drug-sniffing dog has led to federal prison sentences for two men who agents say attempted to smuggle more than half a pound of methamphetamine into Youngstown.

A judge in U.S. District Court last week sentenced 35-year-old Samuel Shipton to 37 months in prison and handed down a 51-month sentence to 40-year-old Jason Hollister.

Both men were convicted of possession with intent to distribute methamphetamine.

According to an affidavit filed in August, a drug-sniffing dog led postal officials to a package holding nine baggies containing 255 grams of crystal meth.

The package, with a Glendale, Arizona return address, was being mailed to a home on the 2600 block of Volney Road in Youngstown.

Leaving most of the meth inside, agents added a GPS tracker. They sprayed the interior of the package with a tracing chemical that can only be seen under ultraviolet light and would be smeared on the hands of anyone opening it.

After the package was delivered, agents say they arrested Shipton at the home on Volney.

Shipton told agents he was just a middleman, saying he was supposed to deliver the package to someone else in Youngstown, according to the affidavit.

After equipping Shipton with a video surveillance device, agents say Shipton drove to a home on the 1500 block of Meadowbrook Drive.

Agents say they watched as Shipton delivered the package to 40-year-old Jason Hollister at the home in Youngstown’s Brownlee Woods neighborhood.

After moving in and arresting Hollister, agents say they also found a marijuana growing operation in the home.

Authorities checked the return address from the package and found it to be fraudulent.