DETECTIVES investigating an alleged serious sexual assault against a child in Whitby are urging the public to help them locate a black Blackberry-style mobile phone. The phone, which has a screen with a keyboard underneath, may contain crucial evidence which can help the investigation. A 50-year-old man and a 29-year-old woman have been arrested in connection with the investigation and released on bail. Anyone with information should call police on 101 or Crimestoppers, anonymously, on 0800-555-111.