PAC launches anti-Tierney ad in 6th District raceSeptember 10, 2012 at 5:03 pm Associated PressBOSTON (AP) – Incumbent U.S. Rep. John Tierney is the target of a new television ad from a political action committee bankrolled in part by billionaire casino mogul Sheldon Adelson. The ad focuses on the Salem Democrat’s family troubles.One of Tierney’s brothers-in-law was sentenced to three years in federal prison for running an illegal offshore gambling operation. A second remains a fugitive.Both have said Tierney was aware of the illegal nature of the operation, something Tierney has denied.Tierney’s wife also pleaded guilty last year to helping file false tax returns for her brother.Republican Richard Tisei is challenging Tierney. The GOP sees the race their best chance to win a House seat in Massachusetts.The YG Action fund, which says it supports conservative candidates, reported spending $818,200 on the ad. Copyright 2012 The Associated Press.