WATERVILLE — Detectives investigating a drug case Wednesday witnessed two men inside a Rite Aid store on Main Street swap items during what officers believe was a heroin transaction.

Deputy police Chief Charles Rumsey said that Zachary Gilbert, 31, of 3 Elm Terrace, and Charles Santana, 26, of 548 Townhouse Road, Vienna, were arrested after the 11 a.m. incident. Gilbert was charged with trafficking in heroin, a class A felony, and Santana was charged with class C felony possession of heroin.

Detective Duane Cloutier and Detective Sgt. William Bonney detained Gilbert and Santana at the front of the Rite Aid. Police searched Gilbert and found 25 bags of a white powder that tested positive for heroin, as well as a small amount of cash, Rumsey said. They found 11 bags of heroin on Santana.

The heroin, which sells for about $16 a bag, has a street value of about $576, police said.

“Based on the investigation, we believe Santana was in the area to purchase those drugs from Gilbert,” Rumsey said.

Cloutier had been investigating heroin trafficking in the downtown area for several weeks and obtained a warrant to search 195 Main St., Apt. 3, Rumsey said.

Detectives conducting surveillance Wednesday morning saw Gilbert, who was staying in a small attic space above 3 Elm Terrace, and Noah Michaud, 22, who is renting the 195 Main St. apartment in the Rite Aid parking lot across the street from the fire station, Rumsey said.

Michaud entered the Rite Aid store with another man later identified as Santana, and Michaud left to go back to his Main Street apartment, he said.

“Several members of the detective division detained Michaud near his residence while other detectives went into the Rite Aid store to locate Gilbert and Santana,” Rumsey said. “While in the store, Detective Cloutier actually found and observed Zachary Gilbert and Santana conduct some hand-to-hand transactions we believe was a drug deal.”

Detectives searched Michaud’s Main Street apartment and found drug paraphernalia, including hypodermic needles and heroin packaging materials, he said. The detectives later searched the attic above 3 Elm Terrace and found more heroin, cash, digital scales, hypodermic needles and drug packaging materials as well as processed marijuana, according to Rumsey.

Gilbert was on probation for a prior conviction for furnishing heroin, a class A felony, so he also was placed on a probation hold in addition to the trafficking charge, and more charges may be forthcoming, Rumsey said.

Gilbert was taken to Kennebec County jail in Augusta. Santana was released on $1,000 unsecured bail.

Both men are scheduled to appear Jan. 13 in Kennebec County Superior Court in Augusta.

Rumsey said Michaud will be charged with possession of drug paraphernalia, a civil offense.

Heroin trafficking had been an issue for police in the city for a number of years, and it seemed to slow down when prescription pill abuse reached epidemic levels, Rumsey said. Police then saw a resurgence of heroin trafficking and use.

“I think you’ll find that to be true in other cities throughout the state,” Rumsey said. “There is a drug problem in the city, and that is not something that is unique to the city of Waterville. However, I think it’s a little surprising that the drug trafficking occurred in the middle of the day inside our stores in the downtown area, so we were very glad detectives were able to conduct that successful investigation and take these drugs off the street.”

Amy Calder — 861-9247

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Twitter: @AmyCalder17