After nearly 40 years, a vital clue may have emerged in the case of missing Fairy Meadow youngster Cheryl Grimmer.Wollongong detectives are investigating the sighting of a child matching the three-year-old's description, six months after she disappeared from Fairy Meadow beach on January 12, 1970.If the claim proves correct, it would mean Cheryl might still be alive.Cheryl disappeared after attending the men's amenities shed with her brothers Ricky and Stephen, following a day at the beach.After the story of Cheryl's disappearance was recounted in the Mercury on August 1, the newspaper was contacted by a 79-year-old Windang man who was adamant he saw Cheryl on Windang Beach in the winter of 1970. The man, who asked not to be named, said the sighting had haunted him for 39 years.''I tried twice to tell police. The second time I was told the case was too old and to just forget it,'' he said.The man said he was with his four-year-old daughter on the beach in June or July of 1970 when a little blonde girl approached them.''A cold westerly wind was blowing and this little girl came from nowhere. She was a blonde girl with a fringe, exactly the same as what was in the paper.''She was wearing a pair of black school shoes with no laces in them. She had the same chubby legs.''She was more interested in our dog than she was in us. I thought, 'what would she be doing running around by herself?'''I asked her, 'How are you?' She just looked at me and ran off.''I followed her back to the caravan park. ''She went into this bus where two dark people were, they were Portuguese or something and I thought, 'how could they have a little girl that fair?'''Despite living at Windang since the 1950s, the 79-year-old said he did not connect the youngster on the beach with the Grimmer case.''About Leg 2five years later the Mercury put out a photo of Cheryl with her father and when I saw it I said 'that's the little girl from the beach'.''The man said he reported the sighting to police, but baulked after being asked why he had not reported the information sooner.''I thought I was interfering with somebody's life. They might have been a legal family so I left it.''Another Mercury article in 1980 prompted the man to contact a detective who was a family friend.''He said he would pass the information on. A couple of days later he said, 'Just forget about it, it's gone on too long'. ''But I've been unable to forget about it. ''I've worried all this time that it was her.''The man described the vehicle in which the child entered as a newly reconditioned early model school bus that was about 6m in length. It had a dark blue body, black mud guards and black roof and ''brilliant'' white wheels.''Somebody must have seen those two people with a blonde girl, if not at Windang then elsewhere moving around in that bus.''The man's sighting has some correlation with Cheryl's disappearance, when a dark skinned man was also reported carrying a small blonde girl wrapped in a blanket leaving the Fairy Meadow surf club amenities block.Wollongong Detective Senior Sergeant Brad Ainsworth said the man's claim was being looked into.He said if police believed it held substance, it would be included in a report to the NSW Coroner.''The report is 95 per cent complete and the coroner will make a directive based on the information provided in the report,'' he said.Cheryl's brother Stephen, 45, of Mt St Thomas, said he would let the detectives decide what to do.''It's been so long,'' he said.