The trial of the first of three defendants charged in connection with the 2010 stabbing death of a Taunton teenager has started. Authorities said Tigan Hollingsworth, 17, was stabbed 13 times after he was chased from a city convenience store in June 2010 during an ongoing dispute with another teenager. The first-degree murder trial of Erving Cruz of Brockton started Wednesday. Prosecutors do not say that Cruz stabbed Hollingsworth; he is being tried under the state’s joint venture law. Authorities allege that Cruz was one of two men who kicked and punched Hollingsworth to the ground before someone else stabbed him.