Brother got kidnapped now kidnapper filed murder case against brother

My brother was kidnapped by group of people who was a contractor in a land dispute and took sign in blank cheque. We lodged fir against him.and his five members. They have not got bail and are absconding .the main culprit went to jail under section of kidnappingand got out of the jail on medical background. But after coming outside he made false half murder case against my brother and the other two witness by giving money to some person for filing case. Now my brotherand witness are in jail. Though my brother is going to get bail. He is also threatening and planning to murder my brother. He also stole around ten lakh rupees but my brother didn't mention it in fir. What all steps to take make all of the culprit arrest and could not get bail. Can my brother kill the kidnapper if he threatens him or plan to kill him.