Dr Singh, who was gunned down in April this year near his home, had threatened to expose his junior action for alleged financial irregularities to the tune of several crores.
The cabinet secretary said the special task force of the state police on Friday arrested three persons, including the two killers.
The official said Dr Sachan gave Rs 7 lakh to two sharpshooters Anant Tewari and Vinod Sharma for eliminating Dr Singh.
Published 17 June 2011, 18:20 IST