Deutsche Bank was one of the institutions linked to the investigation of tax shelters offered by accounting giant KPMG, but now federal prosecutors are taking a closer look at other shelters that DB sold but were not offered by KPMG – namely digital options – and the firms that sold them to the bank. According to The New York Times, the new investigation focuses on variations of a tax-avoidance scheme known as Son of Boss, and includes products such as Cobra (currency options bring reward alternatives), M.L.D. (market-linked deposit) and a Cobra-like shelter known as Homer, named for the character for the TV series The Simpsons, and reportedly sold by Bank One. The Time says Deutsche Bank’s role in creating and selling the questionable products could complicate its effort to negotiate a settlement.