MANKATO — A plan drug-enforcement agents hatched to trade two handguns and $6,500 in cash for marijuana ended with nearly 30 pounds of the drug being confiscated in Mankato and Madelia on Sunday.

At least four men have been arrested, but only three had been charged as of Wednesday afternoon, according to court records in Blue Earth and Watonwan counties.

One of the men, arrested in Mankato, has been charged in Blue Earth County with two counts of being a felon in possession of a firearm and one count of aiding and abetting third-degree drug possession. The two other men were arrested in Madelia and are facing third- and fifth-degree drug charges. All of the charges are felonies.

A confidential informant told an investigator with the Minnesota River Valley Drug Task Force he had “two targets” who wanted to sell a large amount of marijuana and buy handguns, according to court records. When asked how much marijuana the men had to sell, the informant said he had seen one of the men with more than 20 pounds of the drug several times.

A deal was set up Sunday at an undisclosed location in Mankato after the informant contacted 25-year-old David Arnold Arizmendi, who lives in the Maplewood mobile home park in Madelia. A deal was allegedly set up to trade $6,500 in cash and two handguns for 10 pounds of marijuana.

Investigators had ground down the firing pins on the handguns, so they were unable to fire, and only brought $1,500 in what they described as “flash money” to the exchange location, court records said. A camera also was set up in the garage that was used for the bust.

Arizmendi and another man — later identified as 51-year-old Arnoldo Reyna of Brownsville, Texas — were followed to Mankato by another team of investigators who had been watching Arizmendi’s Madelia home. During the set-up, investigators also learned the men were allegedly in the process of receiving a large delivery of marijuana being shipped in the gas tank of at least one vehicle.

After Arizmendi and Reyna pulled into the garage and delivered the marijuana in a shop vacuum, police officers around the building were given a signal to make the arrest. A total of 8 pounds of compressed marijuana was confiscated during that sting.

While that buy was taking place, another group of investigators continued to watch Arizmendi’s home in Madelia. When 27-year-old Faustino Vasquez III of Brownsville, Texas, drove away from the home in a Jeep with two other people, he was stopped on Watonwan County Road 3. He was arrested after a State Patrol drug dog reacted to a suspected marijuana scent under the Jeep.

Rene Villarreal Jr., 18, of Brownsville, Texas, was arrested when he left the mobile home with a large suitcase, court records said. The suitcase was searched after the drug dog also reacted to it. A total of 21 pounds of marijuana, packed in 13 vacuum-sealed bags, were allegedly found inside.

The drug dog also found a suspected marijuana scent on several vehicles outside the mobile home and in a bedroom inside, court records said. Plastic packaging that smelled like gasoline also were found in the bedroom.

Arizmendi, who has been arrested but not charged, was released from prison about a year ago after serving a two-year sentence for second-degree assault with a dangerous weapon. A second-degree attempted murder charge was dismissed in a plea agreement for the September 2004 assault in Madelia.

Reyna is facing the felony weapons and drug charges in Blue Earth County. His bail was set at $25,000 with conditions during a court appearance Tuesday afternoon in Mankato.

Villarreal and Vasquez appeared in Watonwan County District Court in Madelia Tuesday afternoon. Villarreal’s bail was set at $150,000 with conditions and an order for detention was issued for Vasquez.

Two Blue Earth County men were arrested Friday and Saturday after police used a confidential informant to buy a pound of marijuana at a Mankato residence. Investigators, who were expecting to find a large amount of marijuana at that residence, reported recovering a package with a Brownsville, Texas, label on it.

Brownsville, which is about 1,400 miles south of Mankato, is a common starting point for marijuana being delivered north. Many media reports describe drug traffickers being able to buy marijuana in nearby Mexico for about $100 per pound before shipping it to the Midwest, where it can sell for more than 10 times that amount.