The state attorney general's office charged six people yesterday with operating a drug ring that trafficked large amounts of heroin from Pittsburgh to small towns in Crawford County.

A grand jury indictment accused Darryll E. Bishop, 40, of Larimer, and Tashannia M. Clark, 32, of East Liberty, of conspiring to supply four Crawford County residents with 10-bag "bundles" and 50-bag "bricks" over a two-year period. Investigators estimated the total quantity of heroin distributed in that time exceeded $300,000 in street value.

"It's a substantial amount for any community, let alone a relatively quiet one like Conneaut Lake," said Nils Frederiksen, spokesman for Attorney General Tom Corbett.

The 14-month investigation began in October 2006 when narcotics agents acquired information about the drug supply chain by following users in the Conneaut Lake area to dealers, and then the dealers to their suppliers, Mr. Frederiksen said.

Agents used a variety of investigation techniques including surveillance, undercover buys and confidential informants to infiltrate the drug trafficking, Mr. Frederiksen said.

That eventually led investigators to Casey D. McClelland, 25, of Meadville; and Corey J. Blood, 19, Duane A. Zirkle Jr., 20, and Jacob T. Elliott, 20, all of Conneaut Lake.

Each made regular trips to Pittsburgh to meet with Mr. Bishop, also known as "Fish," according to the attorney general's office. Ms. Clark either drove Mr. Bishop to the meetings or helped deliver the drugs, investigators said.

All six face multiple felony charges including conspiracy, heroin possession and delivery of heroin.

The office is still investigating both ends of the supply chain, Mr. Frederiksen said, including how the drugs got to Pittsburgh and their distribution once they arrived in northwestern Pennsylvania.

The attorney general's office believes large-quantity charges such as these will have a longer-lasting effect on the flow of drugs from Pittsburgh to northwestern Pennsylvania than street-level arrests, Mr. Frederiksen said.

"... we're talking about organizations built on trust," he said. ... it takes people time to build those relationships ... to establish the trust needed to move large quantities of drugs."