Doctor testifying in defense of Bergdahl says he suffers from PTSD, personality disorder The doctor said Bergdahl suffered from a several mental health issues.

 -- Former Taliban captive Army Sgt. Bowe Bergdahl has symptoms similar to schizophrenia and is suffering from severe post-traumatic stress disorder (PTSD), according to a forensic psychiatrist who testified in the soldier's trial on Wednesday.

Bergdahl's lawyers called upon forensic psychiatrist and professor Dr. Charles Morgan, who specializes in working with prisoners of war and examined Bergdahl in 2016, in the trial's third day of witness testimony.

Bergdahl, 31, faces up to life in prison after he pleaded guilty to desertion and misbehavior before the enemy for abandoning his Army post in Afghanistan in June 2009.

The closing arguments in the trial could occur as soon as Thursday, military judge Army Col. Jeffery Nance said today. The emotional six day sentencing phase of the trial has included testimony from Bergdahl's fellow soldiers who were injured or killed in the aftermath of his disappearance.

Bergdahl's lawyers hope that the accounts of their witnesses will help reduce his punishment.

Morgan's diagnosis of Bergdahl, who was held by the Taliban for five years before being freed by the group in 2014, included "schizotypal personality disorder," which has similar symptoms to a lesser degree of schizophrenia.

Morgan testified that Bergdahl does not hear voices or have hallucinations, but experiences an ongoing commentary in his mind. He described the former prisoner as odd, eccentric, and preoccupied with a fantasy life.

"His view of the world is pretty bleak," Morgan told the judge in a Fort Bragg courtroom.

According to Morgan, Bergdahl's PTSD stemmed from his abusive childhood home life that included corporal punishment. The PTSD was only exacerbated from his treatment as a prisoner of war.

Morgan's diagnosis of Bergdahl also included "social phobia," a form of anxiety disorder where he fears being thought of as silly or incompetent by others. Bergdahl has a negative image of himself, Morgan said, adding that the soldier is detached, socially awkward, and doesn't form intimate relationships with others.

The doctor also provided insights into Bergdahl's way of thinking, saying that while he's intelligent, he is also "naive."

Morgan compared Bergdahl to a child who jumps into things without thinking about the consequences. Bergdahl wants to do the right thing but doesn't always know the right way to go about it, Morgan said.

"Once [Bergdahl] gets an idea that makes sense, he wants to do it," Morgan said, adding later that Bergdahl knew walking off of his Army post "would get him in trouble."

'People with mental health illness are not dumb'

During his examination, Morgan administered five separate tests on Bergdahl to determine if the soldier was trying to fake a mental illness.

Bergdahl passed every test but one, which Morgan said is designed for civilians -- not prisoners of war -- and could explain why Bergdahl tested so highly on the probability for malingering, or faking an illness.

"The fact that they don't see something wrong doesn't mean there's not something wrong," Morgan said.

"People with mental health illness are not dumb," he added.

When pushed by the prosecution why Bergdahl had told people he faked an anxiety attack while serving in the U.S. Coast Guard that led to his release from duty, Morgan replied that Bergdahl was too embarrassed to admit he was having mental health issues.

'The cat whisperer'

The defense's second witness on Wednesday was an unnamed medical doctor who testified by phone. The woman, who runs a nonprofit animal rescue, met Bergdahl after he contacted her about a feral cat for which he had been caring.

She told the judge that Bergdahl had been able to capture 24 feral cats in San Antonio and brought each of them to her sanctuary. His efforts were so impressive, she said, that she offered Bergdahl a job as a caretaker at the sanctuary -- an offer that still stands, she added.

The woman said the cats, who would normally run away from humans, would surround Bergdahl. He's "the cat whisperer," she said.

ABC News' Conor Finnegan contributed to this report.