Several high-powered senators are continuing their fight against “Zero Dark Thirty,” a film many see as vindicating the use of enhanced interrogation tactics in the hunt for Osama bin Laden.

Sens. John McCain, Dianne Feinstein and Carl Levin fired off a harshly worded letter to Sony Pictures, the studio behind “Zero Dark Thirty,” just before Christmas complaining the film justifies waterboarding, sleep deprivation and other tactics eliminated by President Barack Obama. Now, a Senate panel is revving up an investigation of the film crew’s ties to CIA sources.

Investigators will examine whether the spy agency gave the filmmakers “inappropriate” access to secret material, said a person familiar with the matter. They will also probe whether CIA personnel are responsible for the portrayal of harsh interrogation practices, and in particular the suggestion that they were effective, the person said.

The intelligence committee’s Democrats contend that is factually incorrect.