A 51-year-old Chelsea man already incarcerated at the Kennebec County jail was charged this week with four counts of aggravated trafficking of scheduled drugs after he allegedly sold heroin and crack cocaine to undercover agents last summer in Augusta.

Shaun Bunker allegedly sold a total of 1.01 grams of heroin and 1.46 grams of crack cocaine to agents from the Maine Drug Enforcement Agency over the course of two drug deals in June and July 2016, according to a police affidavit filed Wednesday at the Capital Judicial Center.

Bunker also was arrested last Friday in Augusta on a charge of operating a vehicle more than 30 mph over the speed limit, according to a court document. Police set his bail at $500 cash for that arrest.

For the four drug trafficking charges, a bail commissioner set Bunker’s bail at $50,000 cash with conditions, according to the affidavit filed Wednesday by Brian Wastella, an agent with the Maine Drug Enforcement Agency.

The first alleged sale of heroin and crack took place on June 29 near a business on Bangor Street in Augusta, Wastella wrote. The second took place July 19 on Western Avenue in Augusta. In both cases, police say, he drove a silver vehicle to the deal.

The number of drug arrests rose 2.4 percent in Maine from 2014 to 2015, according to the most current data from the Maine Department of Public Safety. There were 5,943 drug arrests in 2015, up from 5,801 in 2014. About 20 percent of adults arrested on drug charges in both years allegedly trafficked or manufactured drugs.

That data does not reflect how many convictions resulted from those arrests. It also does not suggest whether the increases were the result of more enforcement or a higher volume of trafficking.