Shah, a close aide of Modi, was arrested on July 25, 2010 in connection with the alleged fake encounter of Sohrabuddin case and released on bail on October 29 the same year.
Vanzara was then considered to be close to Modi. In particular, his letter accuses Shah of betraying him and 32 other officers who are now in jail in connection with various encounter cases from Gujarat that CBI is probing.
Vanzara says in the letter that he once adored Modi as a 'god', who could not rise to the occasion under the "evil" influence of Shah.
Shah is Vanzara's co-accused in Sohrabuddin Sheikh and Tulsiram Prajapati encounter cases.