WASHINGTON
--

The Justice Department is investigating whether hundreds of FBI agents cheated on a test of new rules allowing the bureau to conduct surveillance and open cases without evidence that a crime has been committed.

In some instances, agents took the open-book test together, violating rules that they take it alone. Others finished the lengthy exam unusually quickly, current and former officials said.

In Columbia, S.C., agents printed the test in advance to use as a study guide, according to a letter to the inspector general from the FBI Agents Association that summarized the investigation. The inspector general investigation also was confirmed by current and former officials who spoke on condition of anonymity because of the sensitivity of the case.

"There are similar stories for practically every office, demonstrating the pervasive confusion and miscommunication that existed," Konrad Motyka, the association's president, wrote May 13 in the letter obtained by The Associated Press.

Depending on the outcome of the investigation, agents could be disciplined or even fired.

FBI Director Robert Mueller was scheduled to testify Wednesday before Congress, where the new guidelines and the cheating scandal were expected to come up.

The inquiry threatens to be another black eye for the FBI as it tightens controls after years of collecting phone records and e-mails without court approval. The brewing scandal has already upended management at one of the nation's largest field offices.

The FBI had no comment on the investigation late Tuesday.

Motyka's letter urges the inspector general to focus instead on what he called the "systemic failure" of administering the test without consistent rules.