In the FIR, filed by the slain leader's brother Anand Tewari in Ubhaon police state, local SP leader Rajendra Misra has been named as conspirator, ASP K C Goswami said.
Misra had contested the last Assembly election from Madhuban constituency of Mau district and is also a former chairman of Mau Zila Sahkari Bank.
Parashuram Tiwari (35), BSP leader, and his father Vindeshwari Tiwari (70) who was a retired teacher, were shot dead yesterday while returning from neighbouring Mau district allegedly over an old rivalry.
Goswami said a total of four teams have been set up to work out the case.