BOSTON – A jury rejected the defense’s insanity plea and convicted a man of first-degree murder in the killing of 25-year old social worker Stephanie Moulton at the Revere group home where the man lived and Moulton worked.”The facts established that this defendant planned Stephanie’s murder and planned to get away with it,” Suffolk District Attorney Daniel F. Conley said in an announcement of the verdict. “[The defendant] waited until he was alone with her. He took steps to cover up the crime, flee the scene and escape accountability. This verdict was a rejection of the defense that he was not criminally responsible for his actions, and I hope it provides some satisfaction to Stephanie’s family.”Deshawn James Chappell, 30, was found guilty Monday of first-degree murder in the January 2011 killing of Moulton, of Peabody. Judge Jeffrey Locke sentenced Chappell to the mandatory life term without parole immediately following the verdict.The verdict closed a trial that began more than two weeks ago in Suffolk Superior Court.Chappell stabbed Moulton to death in the basement of the group home on Ocean Avenue in Revere operated by North Suffolk Mental Health.Suffolk Assistant District Attorney Edmond Zabin argued during the trial that Chappell waited until he was alone with Moulton in the basement of the home on Jan. 20, 2011. Chappell then attacked Moulton and stabbed her to death. Chappell tried and failed to clean up the scene and then tried and failed to set fire to the building, according to evidence presented at trial. Chappell then took the body and dumped it in the St. George Greek Orthodox Church parking lot off South Common Street in Lynn, near his former home. Police reported Moulton’s body was found partially nude and with deep stab wounds and slashing injuries to her neck.After dumping the body, Chappell abandoned the car, stole clean clothes from a store, sought help from family and made his way to his grandmother’s house, where police later arrested him.Defense Attorney Daniel Solomon argued in the trial that Chappell was insane and responding to voices in his head when he killed Moulton. In closing statements Thursday, Solomon referenced Chappell’s 16-year history of mental illness which included five hospitalizations, a schizophrenia diagnosis and documented reports of hearing voices.Solomon could not be reached Monday evening for comment on the verdict.Zabin argued in closing statements that Chappell’s actions demonstrated that he planned to commit and then tried to cover up the killing to avoid responsibility – indications that Chappell clearly understood what he did was wrong.Zabin also said that only after he was charged with murder did Chappell begin acting bizarrely and tell police he responded to voices telling him to kill Moulton.After the verdict and before sentencing, Kimberly Flynn, Moulton’s mother, recalled a young woman who “would have made a big difference in this world,” according to Conley’s office.