Reza Khan's appointment as Faujdar of Islamabad committed him to politics: only success in politics could ensure his survival. Yet the appointment was an ambiguous one. Reza Khan himself described it as a favour done by Mir Jafar on account of his relationship with the Nawab Alivardi Khan. But the invasion of the Emperor Shah Alam and the concurrent swing in public opinion in favour of the ousted family were to lead the Nawab and Miran to eliminate many Alivardians on suspicion of disloyalty. Between January and June 1760 three favourites of the former regime, Shah Abdul Wahab Khan, Yar Muhammad Khan and Agha Sadiq, son of Agha Baqar, a Dacca zemindar, were all executed. As the alarm of Miran and his father grew, the imprisoned aunt and mother of Siraj-ud-daulah were also killed near Dacca. Ghulam Hussain says that Miran had another 300 suspects on his list for physical elimination after his return from Bihar. Why then was Reza Khan appointed?

One answer may be that Reza Khan's known enmity towards Mir Qasim had made him more acceptable, for Mir Qasim was already a suspect by the beginning of 1760, though not yet an open rival of Miran. While Miran was striving to make himself independent of the English, recruiting European deserters, creating a large body of Rohilla-Afghans, sending missions to the Deccan to recruit there and make contact with the French, Mir Qasim was cultivating Hastings's friendship.