The Crime Branch would probe the case relating to the arrest of a 75-year-old man with an airgun and sword near the residence of CPM state secretary Pinarayi Vijayan in Kannur district on Thursday,official sources said. The CPM state secretariat had demanded a detailed probe into the incident,saying that it should not be taken lightly by portraying the person involved as mentally imbalanced. The CPM described it as an attempt on Vijayans life.