Journalists Associations in Mumbai today began their relay hunger strike to press for a CBI probe into the murder of senior journalist Jyotirmoy Dey. On Monday, media persons had taken out a protest march to demand the immediate arrest of the killers.The Maharashtra government had assured them to accept their demand to bring in a law to protect journalists although it refused to hand over the probe to CBI. It said the Mumbai police should be given a fair chance to investigate the case. Dey was shot dead by four unidentified gunmen at Hiranandani complex in suburban Powai on June 11.