SAN FRANCISCO —A former San Francisco lawyer who resigned from the Bar amid an investigation into funds stolen from his firm has been indicted in an alleged Ponzi scheme.

Federal prosecutors say Robert Tunnell, 72, positioned himself as a successful investor, promising big returns on safe investments, but instead engaged in risky trading activity, losing roughly $7 million of the $10 million investors gave him between 2006 until he was arrested last month. What Tunnell didn’t lose, he used to pay off personal debt, prosecutors say. He gave false reports of gains to investors — mostly family and friends — and created false documents overstating his assets.