CENTENNIAL, Colo. — Defense attorneys in the Colorado theater shooting trial will face new challenges when they try to counter 22 hours of sometimes chilling video of James Holmes talking in a flat, mechanical tone about killing strangers to increase his self-worth.

In short, reluctant answers, he tells a psychiatrist who evaluated him for the court that he felt nothing as he took aim at fleeing moviegoers. He is haltingly awkward as he blurts out that he feared being stopped from committing what he acknowledged was a crime.

His responses are brief and monosyllabic.

Dr. William Reid strung them together to conclude that whatever mental illness Holmes was suffering, he was legally sane when he killed 12 people and wounded 70 others during the midnight premiere of a Batman film.

Defense attorneys on Thursday will finally have a chance to cross-examine Reid and raise questions about the interview. Beyond the legal issues presented in Reid’s testimony, experts say Holmes’lawyers will also have to overcome the emotional impact on jurors of hearing the killer in his own, stilted words.

Judge Carlos A. Samour Jr. has repeatedly told jurors they can only consider Reid’s testimony and the video to help them answer the question of whether Holmes was sane. But experts say Holmes’affect will be hard to ignore.

“They are looking at him as a human being and trying to interpret his soul, his character, his spirit,” said Joseph Rice, managing partner of the Jury Research Institute, a California-based trial consulting firm. “All those things are intangible and very subjective. If he appears to be this cold, unfeeling individual, he’s a threat, he’s scary, he’s not a human. If jurors were to reach those conclusions, they might say this is who the death penalty is for.”