The Maine Drug Enforcement Agency conducted 50 percent more heroin investigations in the first 11 months of 2015 than it did during all of 2014.

MDEA Director Roy McKinney said his office is still compiling its final numbers for 2015 to include December. But he shared the early data in the wake of Tuesday’s announcement that the MDEA and other law enforcement agencies had arrested 15 people in the largest drug investigation in Oxford County history.

Even without including the arrest numbers from the Oxford County investigation and several other recent investigations around the state in December, the MDEA also had arrested more people on heroin charges during the first 11 months of 2015 than during all of 2014.

The data McKinney released on Wednesday shows a stark shift in the MDEA’s focus on the increasingly prevalent heroin trade in Maine in the past two years, drawing the agency’s attention from investigations of other opioids, such as oxycodone pills.

“It crossed somewhere between 2013 and 2014, when the number of heroin investigations exceeded the other opiate trafficking investigations,” McKinney said.

Heroin addiction has surged recently as a widespread problem in rural states like Maine, where a dose of the drug costs less than prescription opiates. A Maine Sunday Telegram investigation this month found that drug cartels in South and Central America have focused on the Northeast, funneling thousands of dollars worth of heroin to states like Maine, which they view as an emerging and lucrative market.

Gov. Paul LePage has called for funding to hire more MDEA agents to deal with the illegal trafficking of drugs, especially heroin, into Maine. The state Legislature last week came up with a plan to increase funding for drug treatment and hire more law enforcement agents, though the governor has criticized the comprehensiveness, detail and timing of the plan.

The MDEA is one of the law enforcement agencies in Maine that investigates drug trafficking. Local police departments, state police, county sheriffs’ offices and federal authorities do work in overlapping areas, but McKinney believes the MDEA’s numbers are representative of those that other agencies are seeing as well.

McKinney said that the decline in investigations of other drugs is attributable to the fact that agencies are redirecting much of their efforts to stem the flow of heroin into Maine.

“We’re at a certain capacity and can only do so much,” McKinney said, explaining why the number of heroin investigations has surpassed the investigation of other opioids.

As recently as 2011, the MDEA had conducted as few as 50 heroin investigations in the state compared with 324 investigations into the trafficking of other opioids. McKinney said a single investigation would be counted, for example, for each undercover drug purchase as part of a larger operation targeting a particular drug ring.

By 2013, the MDEA conducted 174 heroin investigations compared with 261 investigations into other opioids. That balance tipped in 2014 with 243 heroin investigations to 185 investigations of other opioids.

By the end of November 2015, the MDEA had investigated nearly three times as many heroin cases, 369, as other opioid cases, 130.

The trend also is shown in the MDEA’s arrest numbers from the past several years. The agency made 127 heroin arrests in 2013, 216 in 2014 and 226 so far in 2015. As the number of heroin arrests has risen, the agency’s arrests for other opioid drugs have declined, from 243 in 2013 to 180 last year and 133 so far this year.

During the same period, MDEA arrest numbers for powdered cocaine, crack cocaine and methamphetamine also have risen, but to a lesser degree than the heroin arrests.

In 2013, the agency arrested 92 for powder cocaine, 34 for crack cocaine and 51 for methamphetamine. In 2014, it arrested 84 for powder cocaine, 29 for crack and 63 for meth. In 2015, the arrests have risen to 100 for powder cocaine, 36 for crack and 79 for meth.

McKinney emphasized that those numbers were just for his agency, not all law enforcement agencies statewide.

In methamphetamine cases, McKinney said the agency has investigated a steadily rising number of home-grown meth labs in Maine, from seven in 2011 to 53 so far in 2015, as criminals become more adept at making the drug here rather than importing it.

“We have more meth lab-related incidents (in Maine) than the other five New England states combined,” McKinney said.

McKinney said what has been notable in meth lab investigations is that the numbers in the most rural areas like Aroostook County have remained steady, while investigators are discovering more methamphetamine in the urban areas of Cumberland, York and Penobscot counties. And more often, uniformed law enforcement officers find evidence of in-home and in-vehicle labs and chemical dumps rather than detectives on undercover operations. In Cumberland County alone, MDEA investigated only one meth lab incident in 2014 and then nine so far in 2015.

“Our concern was an officer was going to come across something and not know what it was,” McKinney said.

He expects the numbers for all of 2015 will reflect the changes in the illegal drug trade in Maine more dramatically when the December statistics are added in.