BOSTON – The defense cited doctors’ testimony and years of mental-health records to show a man was insane and responding to voices when he killed a 25-year-old social worker in the group home where the man lived.”This is a very sick person, and he has been for years, and still is and is still going to be by all accounts,” Defense Attorney Daniel Solomon said in Suffolk Superior Court Thursday. “There are issues here that are difficult, there are issues that are tenuous, but the fact is the Commonwealth has failed in its duty, its obligation, to prove to you beyond a reasonable doubt, with moral certainty, that this man did not suffer from a major mental disorder at the time this happened.”The prosecution, however, cited the defendant’s decisions immediately surrounding the homicide to show the man planned and subsequently tried to cover up the killing.”He comes in here and claims at the time he was insane,” Suffolk Assistant District Attorney Edmond Zabin said. “This is the man who killed (the victim), who dragged her body out of that building. This is a man who did everything he could to cover up the crime … drove to Lynn, drove to Dorchester, asked for money, asked for people to harbor him ? and when caught by police he lied about what happened. That is the man who claimed he was insane? Please.”Deshawn James Chappell, 30, is charged with first-degree murder for the fatal stabbing of Stephanie Moulton on Jan. 20, 2011 at the Revere group home where Chappell was a resident and Moulton was employed.The trial began nearly two weeks ago in Suffolk Superior Court in Boston, and each side presented its closing arguments Thursday morning.Solomon acknowledged the killing was “brutal.” But he asked jurors to consider reason rather than “human emotions, human considerations, human thoughts that can’t be a part of your decision.”Solomon repeatedly cited “1,800 pages” of medical records detailing Chappell’s history of mental illness, which includes five hospitalizations, a schizophrenia diagnosis and a documented history of hearing voices.Solomon cited experts’ testimony – testimony for both the prosecution and defense – that Chappell suffered from mental illnesses. He noted two experts “both said he’s crazier than a bedbug.”And Solomon told the jury that Chappell’s actions were “disorganized” and did not meet the standards of first-degree murder.He said there was no indication of malice or conflict between Moulton and Chappell. Solomon argued Chappell’s beating of Moulton was not “sustained,” and Chappell cut Moulton’s throat – fatally injuring her but killing her quickly.Solomon also questioned whether a sane person would do as Chappell did and try – and “pathetically” fail, as Solomon said – to mop up Moulton’s blood and attempt to burn down the house with the body inside. Solomon also questioned whether a sane person would choose to dump the body in a Lynn parking lot rather than in the nearby Lynn Woods or the ocean.As for premeditation, “(Chappell) doesn’t know what happened; to this day he doesn’t know what happened,” Solomon said.But Zabin said the premeditation “doesn’t mean you have to have planned the perfect crime.”Zabin argued that Chappell made conscious decisions before and after the killing. Zabin said Chappell waited until he knew he and Moulton would be alone in the group home. Chappell lured the victim to the basement and attacked her, tried to sexually assault her and beat her “until she was nearly unrecognizable,” according to Zabin.Chappell then tried to cover his tracks, choosing to try to clean and then try to destroy the crime scene, Zabin said. Chappell found the defendant’s keys and chose to take her car to an unused parking lot near where he used to live, Zabin told the jury.”The question in this case is not whether or not the defendant suffers from schizophrenia (or other mental issues) …that’s not the issue, it doesn’t matter,” Zabin said. He said what mattered was “whether at the time of the killing (C