An Ohio man has been executed for shooting and killing his three sleeping sons in 1982.Reginald Brooks, 66, shot his sons, aged 11, 15 and 17, shortly after their mother filed for divorce.Brooks\' execution was the first lethal injection in Ohio in nearly six months.The Ohio Supreme Court rejected a request to halt the execution because Brooks suffers from schizophrenia. Prosecutors said his mental illness did not cause the murders.Beverly Brooks found her sons dead when she returned from work. On Tuesday, she and her family sat silently during the execution.They wore white t-shirts bearing photos of her children, who were 11, 15, and 17-years-old when they were killed.\"Our nephews are gone, and they\'ll never be replaced,\" Ms Brooks\' sister, Monica Stephens, told the Associated Press news agency.\"The memories we\'ll always have. The what-ifs we\'ll always have.\"The Supreme Court\'s decision came hours after a state appeal court denied Brooks a chance for a new trial.Ohio Governor John Kasich denied clemency, and the US Supreme Court refused to block the execution.