When angry collectors started suing Knoedler & Company for selling dozens of multimillion-dollar forgeries, the gallery’s former president, Ann Freedman, insisted that she and her colleagues had had no reason to think that any of the paintings were counterfeit. “If Ann Freedman had any questions about these works, she and her husband would not have invested hundreds of thousands of dollars in them,” her lawyer, Nicholas A. Gravante Jr., said of the paintings attributed to modern masters like Robert Motherwell, Mark Rothko and Jackson Pollock. Now, newly released documents in a continuing civil case show that at least one of the works bought in 2000 by Ms. Freedman herself contained a prominent clue that something was awry. The artist’s signature was spelled incorrectly: Pollok instead of Pollock.