A substitute teacher at Mountain Valley Middle School in Mexico was arrested this week along with two other local men and charged with smuggling heroin and cocaine into Maine.

Matthew Duka, 25, of the Oxford County town of Hanover, was arrested Wednesday in Auburn after being stopped by Maine State Police, Rumford police said Friday. Duka and a passenger in his vehicle, Kenneth Armstrong, 26, of Mexico, were returning from Portsmouth, New Hampshire, after buying cocaine there, police said. Police found less than 5 grams of cocaine and $3,488 in the car.

Police had begun investigating Duka in February after getting a tip that he was involved in smuggling heroin into Maine from Massachusetts, for sale in the Rumford, Mexico and Dixfield areas. Police used an undercover officer to gather evidence.

An undercover officer with the Maine Drug Enforcement Agency bought heroin from Duka in Mexico, police said. That officer learned that Duka had been hired by Angel Cabrera, 25, of Mexico to make a series of trips to Boston and pick up hundreds of “dosage units” of heroin and crack cocaine. Duka brought the drugs back to Cabrera and others in Dixfield, where the drugs were prepared for sale.

Police said their investigation had “not yet” confirmed any drug sales made to local students, but said Duka did try to sell drugs to an 18-year-old student, who declined.

Duka and Cabrera each were charged with two counts of criminal conspiracy to commit aggravated importation of drugs (heroin and cocaine) and two counts of conspiracy to commit aggravated trafficking of drugs (cocaine and heroin). The charges are Class B felonies. Armstrong was charged with illegal importation of drugs, a Class B felony, and unlawful possession of drugs, a misdemeanor. Information on their arraignments was not available Friday night.

Duka was added to the Regional School Unit 10 approved substitute teacher list in October 2016 and subbed off and on at the middle school through March, Deborah Alden, superintendent of schools for the district, said in an email Friday. He also substituted six days at other schools in the district and he volunteered to help the wrestling team at Mountain Valley High School in Rumford this past winter, Alden’s email said.

The email also said Duka had undergone a criminal record check and background check before being hired as a substitute and that he was taken off the substitute list as soon as police informed school officials he was being investigated.

In another investigation into drug sales in western Maine, Rumford police said that Sean Blalock, 32, of Wolcott, Connecticut, was arrested Wednesday and charged with trafficking of heroin. Blalock had supplied an estimated 2,500 dosage units of heroin to be sold in western Maine, police said. He was arrested in Connecticut.

The MDEA, state police and police in Rumford, Mexico and Dixfield are continuing the investigations. Police expect more arrests in connection with the Duka and Cabrera investigation.

Ray Routhier can be contacted at 210-1183 or at:

rrouthier@pressherald.com

Twitter: RayRouthier