OSKALOOSA — The prosecution and defense gave their closing arguments Tuesday afternoon in the first-degree murder trial of Brad Arterburn in Mahaska County District Court.

Arterburn, 27, of Oskaloosa, has been charged with the first-degree murder of his mother’s boyfriend, Robert Henry “Hank” Horovitz, 58, of Davenport, on June 19, 2011. Arterburn entered a plea of not guilty in Mahaska County Court July 12, 2011.

Prosecutor Denise Timmins argued that Arterburn committed a “heinous act” and took the life of Horovitz.

“Your duty is to seek the truth,” she said.

She argued Arterburn acted with deliberation and malice.

“The defendant has the burden to prove insanity,” she said.

Defense attorney Ken Duker argued there was no financial motive for Arterburn’s actions. Also, he argued the state’s professional witness diagnosed Arterburn in his clinical judgment — subjectively and not objectively. He argued that the defense’s witnesses utilized objective  as well as subjective tests in diagnosing Arterburn. He also argued that Arterburn acted in self-defense and was not rational when he thought he was defending himself against his abuser Dave Myers.

Duker’s conclusion was that Arterburn was not guilty by reason of insanity.

In follow-up statements, Timmins argued that if Arterburn truly believed he had killed his abuser — Myers — and not Horovitz, wouldn’t he have told everyone about it? Instead, when police arrived on scene, he was calmly smoking a cigarette on the deck behind the house.

Testimony from two mental health professionals Tuesday morning set the stage for closing arguments.

Psychiatrist Dr. James Dennert testified for the prosecution and clinical psychologist Dr. Craig Rypma testified for the defense.

Dennert examined Arterburn in September and conducted interviews with him and reviewed records and testimony concerning the case.

Dennert determined that Arterburn’s state of mind was such that he understood the nature and consequences of his actions, he understood the difference between right and wrong and acted with intent.

Dennert also determined that Arterburn was not in a disassociative state at the time of his interview with DCI agent Adam De Camp.

Dennert said that when Arterburn said he was having flashbacks during court testimony Monday, he was not having one in psychiatric terms. Dennert said he did not indicate that he was reliving actual events while in the courtroom. He was likely having vivid memories of abuse.

Also, Dennert said that Arterburn did not have a psychotic episode on June 19, 2011.

Dennert said he diagnosed Arterburn with a depressive disorder.

Rypma said he examined Arterburn and administered the MMPI test, an objective test of a person’s state of mind. He said the results of the test showed that Arterburn had elevated results to indicate psychotic thinking and a mood disturbance.

Rypma also said Arterburn has an IQ of 91, which is on the low end of the normal category.

Rypma observed Arterburn on the witness stand Monday and said that showed a person with a 91 IQ interacting with people whose IQs were 120. It also showed that Arterburn is a person who is open to suggestion and easily led to desired answers.

Rypma said Arterburn suffered from “black feelings” throughout his teen years. Rypma said those are similar to alcohol-induced blackouts people have.

Rypma said a review of the DCI interview indicated that Arterburn was confused during questioning.

Rypma said he determined that Arterburn could not understand the nature and quality of his actions on June 19, 2011. He also couldn’t distinguish between right and wrong.

The trial resumes at 8:30 a.m. Wednesday with the jury going into deliberations.

Herald Editor Duane Nollen can be reached by email at oskynews@oskyherald.com