Abuse which testimony has revealed Cody Posey's father and stepmother inflicted over many years, fits classic models, a psychologist testified on Thursday on behalf of Posey's defense.

Posey, 16, admits to shooting his father, Delbert Paul Posey, on July 5, 2004; along with his stepmother, Tryone Posey, and his 13-year-old stepsister, Marilea Schmid. Posey was 14 at the time. The crimes occurred on Sam Donaldson's Chavez Canyon Ranch in Lincoln County, where Delbert was ranch manager.

While Johnson described Posey as "bright" -- she tested his IQ at 115 -- she said socially and emotionally he could not gain his father's acceptance and was "struggling for his life ... and his manhood."

Posey and defense witnesses -- which have included students, teachers, ranch hands and a Sunday school teacher -- have testified Posey suffered what Johnson termed "severe" verbal, physical, emotional and sexual abuse. She said such abuse generated fear, and heightened Posey's despair and his feeling of being "unsafe in the word."

In addition, testimony has depicted the parents as preventing Posey from socializing with friends and extended family, and from participation in school and church events.

"Those are all the kinds of things that many parents would love to have their children interested in," Johnson said. "Depriving kids of things that can be so important to their welfare and their ability to grow ... is really self-defeating."

According to Johnson, participation with peers is "an intense need that kids have" and "good for them given the right peers."

However, when children are abused physically and sexually, she said they develop a fight or flight response. While she said externally Posey put on "a good face" for others, he was always "on alert for the next awful encounter."

She cited as an example that Posey hoped to play eighth grade football the next year at Hondo, where he had friends; but when his father pulled Posey from the school and reneged on the promise, Johnson said Posey's hopelessness increased.

Then summer vacation arrived. Johnson said Posey described summer as "'a prison without bars'" because he didn't even have school as a safe haven, and "his depression increased."

As an abused child matures physically, she said, they begin to feel they have power to defend themselves. In response to fear and terror, they now feel they can fight back.

Johnson diagnosed Posey with a "combination of disorders that come from responding to stressful circumstances." Among them were post traumatic stress disorder, depression -- for which Posey was prescribed Zoloft -- and attention deficit hyperactivity disorder.

"He was reacting to things that were going on in his life that in ways were painful for him and for other people as well," Johnson said, pointing out it's often why he would forget homework, for which he would be punished. "(It) created problems at home and school."

While she said family is "extremely important" in treating such mental illnesses, it was in Posey's family where much of the stress was rooted, to the point that she believed Posey was in mental anguish when he pulled the trigger.

Posey testified that on the morning of the shooting he and his father got into an argument and his father hit him. Coming on the heels of the night before, when Posey said his father tried to force him into sex with his stepmother, Johnson said that aroused various extreme emotions: anger, rage, terror and fear.

"I believe that his emotional condition at that time would have impaired or gotten in the way of his ability to reason," Johnson said. "I believe that his control ... over his behavior was reduced, was impaired."

She also believed it impaired his judgment over the wrongness of taking a life.

"It seems to me that Cody was becoming less in control of his emotions," Johnson said. "Things were becoming more scarier in the house."

On cross examination, Grisham brought out that during Johnson's evaluation Posey admitted he carefully weighed his options to escape his perceived hell: telling authorities, running away, or killing because "'my world would be better off without them.'"

Grisham said Posey's admitted thought process was "indicative of an intent to kill" when he replaced snakeshot with lethal ammunition; wore gloves so as not to leave fingerprints; secreted the gun to slip it past his father; shot Tryone first so she wouldn't call 911; ambushed his father and Marilea; smashed a window to simulate a breaking and entering; then buried the bodies and disposed of evidence.

"People who are psychotic ... don't think about covering up their crimes, do they?" Grisham said.

Listening to the day-long testimony, Posey appeared more morose than usual as his life was laid bare. He has been following the trial with apparent interest. Mitchell told the Daily News when psychologists interviewed Posey, he was told their conversations were "confidential."

"Then we get this stuff into the courtroom and we crucify (him) with it," Mitchell said. "It's getting to him."