Jury selection has begun in the murder trial of an East Boston man who was mistakenly released on bail because of a clerical error. Jean Torres Vargas was originally charged with aggravated assault and battery in the 2010 beating of Michael Costa. Vargas remained in custody after that arrest. After Costa died 13 months later of his injuries, Vargas was indicted on a murder charge. But 10 days later, Vargas posted bail. Because a warrant charging him with murder was issued in the wrong name, he was not held. Vargas was captured about a month later.