In an August release announcing the charges against seven oil companies, Purdon said, "These allegations of violations of the Migratory Bird Treaty Act by companies operating in North Dakota’s oil patch should be troubling to those interested in preserving North Dakota’s rich heritage of hunting and fishing."

The U.S. district court in North Dakota dismissed the case in January.

"None of these bird species is endangered, and many commercial activities result in vastly more accidental bird deaths on a regular basis," Gingrich said in his letter.

Gingrich recommends that the Smith subpoena records and also see why the U.S. attorney decided to bring charges.

"I ask that you use your authority as Chairman of the House Committee on the Judiciary to subpoena decision documents from U.S. Attorney Purdon’s office to determine why he decided to prosecute the case and explore whether he should be removed from office for deliberate abuse of power," Gingrich continues in the letter. "I further suggest that you investigate the involvement of officials at the Department of Justice in Washington, D.C."

Purdon in his original statement said, "At the North Dakota U.S. Attorney’s Office, we are committed to enforcing laws that protect North Dakota’s outdoors and to providing companies who follow the law with a level economic playing field."