This month, help is needed to solve the mystery surrounding the murder of Neighbourhood Watch co-ordinator Janet Brown. On 10 April she went to work in Oxford and returned home as usual. A friend telephoned her around 8.00pm and she was fine, but her body was found the next morning. Help is needed to identify several cars seen in the area at the time she died. And police are also hoping to identify a man caught on camera selling stolen jewellery. I