Yusuf, nephew of former Rashtriya Janata Dal (RJD) MP Mohammad Shahabuddin, was shot dead in Siwan on Friday night.
Shahabuddin was elected four times as a Member of Parliament (MP) from Siwan. He was imprisoned for 11 years for his involvement in the murder of RajivRoshan.
The death of Yusuf comes less than a week after a Bihar court framed charges against Shahabuddin and seven others in connection with journalist Rajdev Ranjan's murder case.
Shahabuddin has been listed as "A" type history sheeter by Bihar government which means that a criminal who is beyond reforms.
Further details are awaited.