Marathon bombings mastermind Tamerlan Tsarnaev was living on taxpayer-funded state welfare benefits even as he was delving deep into the world of radical anti-American Islamism, the Herald has learned. State officials confirmed last night that Tsarnaev, slain in a raging gun battle with police last Friday, was receiving benefits along with his wife, Katherine Russell Tsarnaev, and their 3-year-old daughter. The state’s Executive Office of Health and Human Services said those benefits ended in 2012 when the couple stopped meeting income eligibility limits. Russell Tsarnaev’s attorney has claimed Katherine — who had converted to Islam — was working up to...