By Vassia Barba Brian Dorsey, 52, was executed by lethal injection Tuesday night at the state prison in Bonne Terre, Missouri. The US Supreme Court declined his appeals, and Governor Mike Parson rejected a clemency request on Monday. Dorsey, formerly of Jefferson City, was convicted of killing his cousin Sarah and her husband Ben Bonnie on Dec. 23, 2006, at their home near New Bloomfield. Abraham Bonowitz, executive director of Death Penalty Action, told The Mirror ahead of the execution: “Clemency is supposed to be about whether a person is worthy of mercy, not a retrial of the facts of the c…