CONCORD — Federal prosecutors charged eight southern New Hampshire men and one from Massachusetts with engaging in a cocaine drug trafficking conspiracy over the past two years.

The charges were brought on March 6 but U.S. Attorney Scott W. Murray convinced a federal judge to seal the files until all the defendants were arrested.

The indictments followed a year-long investigation that involved federal, state and local law enforcement partners, Murray said.

“As alleged, these individuals distributed crack cocaine in New Hampshire for several years and disrupting drug trafficking organizations like this one is a critical part of our mission,” said Joseph R. Bonavolonta, special agent in charge of the FBI Boston division. “The FBI will continue to focus our energy, and expertise to help our law enforcement partners stem the tide of drugs flooding our streets.”

According to federal documents, the group possessed with the intent to sell and did distribute at least 280 grams of cocaine and crack cocaine.

Along with the federal felony drug sale indictment, prosecutors filed notice to try and obtain the drug dealers’ property through forfeiture.

Officials offered few details about the group beyond their names, addresses and in some cases their nicknames in the crew.

The defendants are:

• George Cruz, 30, Nashua;

• Lawrence Fortenberry, 65, Nashua;

• William Greenleaf, 42, Nashua;

• Donald Johnson, 34, Nashua;

• Isaiah Kinard, 29, Manchester;

• Marvin Morrison, 36, Nashua;

• Terray Morrison, 30, Nashua;

• Melvin Nooks, Jr., 28, Fitchburg, Mass.;

• Melvin Stanford, 40, Manchester.

If convicted, Morrison, Stanford, Cruz, and Nooks Jr. face a mandatory minimum of 10 years in prison and a maximum sentence of life as well as a fine of up to $10 million, prosecutors said.

The other defendants face a maximum sentence of 20 years in prison and a fine of up to $1 million.

Cruz was the only one arraigned Friday and he pleaded not guilty.

Cruz was held in federal custody pending a detention hearing scheduled for next Tuesday afternoon at 3:30 in U.S. District Court in Concord.