A 1985-batch IPS officer from the state, Mohananey took over as head of the Sikkim police yesterday after he was relieved from the Intelligence Bureau on Saturday.
The post had been lying vacant after Jasbir Singh retired as Director General of Sikkim Police in October last year.
58-year-old Mohananey had an expertise on crucial desks in the central agency which included Kashmir and Pakistan. He was also posted in Pakistan from late 1990s to early 2000 before being sent to look after the Kashmir desk.
An outspoken officer, Mohananey was able to bust a huge hawala racket in which some senior separatist leaders from Jammu and Kashmir were also involved.
He will be now leading the 7000-strong force till his retirement in August 2017 or till further orders.