BISMARCK, N.D. (AP) — Three members of a tribe on the oil-rich Fort Berthold Indian Reservation in North Dakota are accused of accepting hundreds of thousands of dollars in bribes and kickbacks from a construction contractor.

Court documents unsealed Thursday show Randall Phelan, 55, of Mandaree, Delvin Reeves, 52, of Watford City, and Frank Grady, 52, of Hardin, Montana, are charged with conspiracy and federal programs bribery. They each face up to 15 years in federal prison if convicted.

Phelan is an elected tribal business council member of the Mandan, Hidatsa and Arikara Nation, also known as the Three Affiliated Tribes; Reeves is a paid tribal government employee; and Grady was a tribal business council representative from 2014 to 2018, according to court documents filed in federal court in North Dakota.

Prosecutors said Phelan and Reeves solicited and accepted bribes and kickbacks from a contractor from 2013 to this year. Court records said Grady solicited and accepted bribes and kickbacks from 2016-2017. Court records allege that all three men used their official positions help the contractor’s business, including by awarding contracts and advocating for the contractor with other tribal officials.

Attorneys listed for Phelan and Reeves did not immediately return calls seeking comment Friday. Court records did not list an attorney for Grady.

Three Affiliated Tribes Chairman Mark Fox and CEO Scott Satermo also did not immediately return email and telephone messages on Friday.

The contractor is named only as CC-1 in court records. Prosecutors said the business received more than $17 million over the past decade for construction work on the 1,500-square-mile (3,885-square-kilometer) reservation in west-central North Dakota. The contractor has pleaded guilty to bribery and has cooperating with prosecutors, according to court records.

The reservation accounts for about a fifth of oil production in the state, the No. 2 oil producer behind Texas.