The five-year-old malpractice suit against Washington, D.C.-based plaintiffs firm Cohen Milstein Hausfeld & Toll concluded Thursday when a D.C. Superior Court jury returned a judgment for one of the plaintiffs to the tune of $500,000. The jury trial lasted nearly four weeks.

Thomas Prousalis Jr. and Gayle Prousalis sued Cohen Milstein, along with partners Herbert Milstein and Lisa Mezzetti, in 2003, alleging the defendants had botched the Prousalises’ underlying case against their stockbroker. According to the complaint, Cohen Milstein failed to file witness or exhibit lists in that case, and withdrew as counsel on the morning of an arbitration hearing. As a consequence, the complaint says the Prousalises were forced to abandon their case.