WASHINGTON (Reuters) - A decision by the U.S. attorney general to probe deeper into alleged CIA abuse of captured terrorism suspects may not land anyone in jail, and it could just produce more headaches for President Barack Obama who wants to move on.

The logo of the U.S. Central Intelligence Agency is shown in the lobby of the CIA headquarters in Langley, Virginia March 3, 2005. REUTERS/Jason Reed

A report issued by the Central Intelligence Agency’s inspector general this week offered a possible road map for building cases.

It gave graphic details about interrogations going beyond approved techniques, recounting threats to kill prisoners’ families, a fake execution, a use of a power drill to scare a prisoner and the fact that accused September 11 mastermind Khalid Sheikh Mohammed was “waterboarded” 183 times.

But legal experts say special prosecutor John Durham, named by Attorney General Eric Holder to lead the investigation, will face high hurdles to sending anyone to jail.

“I think it’s going to be pretty challenging because if you look at the torture statute it is very narrowly drafted,” said Thomas McDonnell, a law professor at Pace University in New York.

“Even using the drill as a threat, according to the torture statute, there was no physical harm so there has to be severe mental harm. But the statute then defines as it having to be prolonged mental harm,” he said. “So unless you can show that it produced severe and long mental harm, it may not even fit.”

The American Civil Liberties Union sued for the CIA report to be made public in the hopes of showing that the Bush administration engaged in torture to coerce information from terrorism suspects in violation of U.S. and international law.

The group has pushed for the prosecution of interrogators and those who authorized the techniques.

But regardless of whether charges are filed or not, Obama will likely face criticism from more liberal Democratic supporters who want former Bush officials prosecuted.

Republicans, including former Vice President Dick Cheney, have criticized the investigation as undermining national security.

POLITICAL HEADACHE AHEAD

“It’s almost a no-win,” said Larry Sabato, a political science professor at the University of Virginia. “This is bound to be a moderate-sized to massive controversy depending on what the recommendations are.”

He said that when Obama was trying to push through his top legislative priorities like overhauling the $2.5 trillion healthcare system, “you don’t need additional controversies.”

Another legal complication in the prisoner abuse cases is that some of the interrogations were done outside the United States, and many were done years ago which raises questions of whether they can still be prosecuted.

Glen Donath, a former federal prosecutor and now a partner at the law firm Sonnenschein Nath and Rosenthal, said that the prisoners would also have a motive to complain after being held for so long under such conditions.

“All of these things would be firing off against wanting to prosecute this unless the evidence was compelling,” Donath said, adding that it would have to be along the lines of an interrogator trying to kill someone or trying to inflict harm “with no motive of gathering intelligence.”

ALCU officials counter that there is a mountain of evidence that U.S. government agents used torture methods and there should be prosecutions.

“These are heavily documented crimes ... there are tens of thousands of pages that have been produced related to the CIA’s rendition, detention and interrogation program and it’s not a context in which there are disputes about crucial facts,” said Jameel Jaffer, director of ACLU’s National Security Project.

One of the biggest hurdles Durham likely faces is that Bush Justice Department lawyers wrote lengthy memos authorizing the CIA to use coercive techniques. Interrogators could use those memos as a defense.

The ACLU has also called for prosecuting the attorneys who offered extensive legal backing for the techniques, Steven Bradbury, Jay Bybee and John Yoo. But that too poses problems for Durham.

“I think it’s pretty much close to impossible to prove that in their minds and heart of hearts they understood that the law provided otherwise but they were just doing what their masters wanted,” Donath said.