The police raided Gangta village last night and arrested one Pintu Lal Dev, who is the brother-in-law of Jha's sister Munni Devi, Senior Superintendent of Police A K Satyarthi said.
Seth was being questioned by the Special Task Force in connection with the murder case of Brajesh Kumar and Mukesh Kumar, he said.
Satyarthi said that six suspects detained for interrogation have been let off on bond as their role in the engineers' murder case could not be established.
Two engineers of a private road construction company were shot dead by unidentified assailants near the road construction site at Shivram Chowk on December 26 allegedly after the firm failed to meet the ransom demand.
Santosh Jha, incarcerated in a Gaya jail, was under the scanner of investigators, the police officer said.
STF officials had yesterday inspected the spot of murder of the two engineers and recovered some used cartridges of AK-47 and country-made pistol, besides leaflets of Bihar People's Liberation, a gang being run by Santosh Jha.

Latest News  from Bihar News Desk