A woman who gave evidence against Dave Lee Travis told ITV News she is worried that the verdict recorded today could "prevent other people from coming forward."
However, she urged people not be "put off" in contacting the police.
Travis, 68, was found not guilty of 12 indecent assault charges and the jury at London's Southwark Crown Court failed to reach verdicts on two other charges.
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The move, which had been expected, was made on the recommendation of FBI disciplinary officials.
The voicemail left on a landline was not heard by a state DoT employee until Friday.