New Delhi, The CBI will challenge before the Supreme Court the acquittal of Abdul Karim Tunda in the 1993 serial train blasts case by a special court in Ajmer, officials said Friday. The agency said 12 people have been convicted in the case so far including Irfan and Hamir-Ul-Uddin, who were sentenced to life imprisonment by Judge Mahaveer Prasad Gupta of the Terrorist and Disruptive Activities (Prevention) Act (TADA) court on Thursday. The judge acquitted Tunda.