A special investigation team (SIT) has been set up to ascertain the cause behind the murder of Maharajganj BJP MP Janardan Singh Sigriwal's close aide Keshavanand Giri at Majhi in Saran, around 70km northwest of Patna.

Saran superintendent of police (SP) Pankaj Kumar Raj said on Friday that the SIT would be headed by a 2013-batch IPS officer Manish Kumar, who is posted as assistant superintendent of police of Saran.

"The SIT will cover the possible angles," he added.

The body of Giri, a well-known grassroots leader, was recovered from a deserted place in the outskirts of Mathia village on Thursday morning. The family members told the police that three persons around 11pm on Wednesday woke up Giri.

"Giri was asked by the men (visitors) to accompany them. He got dressed in a dhoti, kurta and a jacket and went out with them, telling his family that he would be back in an hour. His body was lying in a pool of blood with a bullet injury in his head," said Majhi police station house officer Prabhakar Pathak.

The SHO said the assailants could have known Giri, as he couldn't raise an alarm. His family started a search only when he didn't return home. The body was found barely 500 metres from his house at Raghunathpurgiri Mithia village, Pathak added.

The deceased's family members had told the police on Thursday that Giri didn't have any personal enmity. "The murder seems to be politically motivated as he was often seen with the MP (Sigriwal)," said a relative.

Supporters of the slain leader had blocked the road and held demonstration to protest the incident. Giri had contested the last Assembly elections from Majhi as Independent but lost.

In 1985, Giri had unsuccessfully contested the Assembly polls from Jalalpur on a BJP ticket. He was later elected as sarpanch.

"For the past few months Giri was not into active politics. But he used to take part in social activities," Saran superintendent of police Raj said, adding that the case would be cracked soon.

The SIT carried out raids at different hideouts of the suspected assailants on Friday but nobody could be arrested. "Raids are underway. We hope to catch the culprit soon," the SP said over the phone from Chhapra, the district headquarters of Saran.

Senior BJP leader Sushil Kumar Modi called on the family members of the slain leader on Friday and promised help.