"The arrested man is being brought to Bihar for interrogation. It is a major breakthrough in the case," a police officer said.

He, however, refused to give more details.

Two days ago, the SIT arrested seven people from different villages in Bhojpur district in connection with the case, the official said.

Brahmeshwar Singh, in his 70s, was killed by unidentified gunmen Friday morning in Ara town, district headquarters of Bhojpur, about 60 km from here. He founded the Ranvir Sena in 1994. The Sena, an outlawed upper caste private militia, was involved in several massacres.

The killing had sparked large-scale violence and arson in Ara. The supporters had indulged in violence even during the funeral procession of Bhahmeshwar Singh Saturday.

On a tip-off, the SIT team raided a house Tuesday night in Jamshedpur and arrested the close aide of the legislator Sunil Pandey.

"The SIT expect vital information from him," a police official said.

Pandey, a criminal turned politician, was allegedly a conspirator in the killing of the Ranvir Sena chief. But neither police nor SIT have officially named him.

Ironically, Pandey, JD-U legislator from Terari assembly constituency, and his brother Hulas Pandey, who is also a JD-U legislator, were considered close to the slain Ranvir Sena chief. Both brothers were active supporters of Ranvir Sena in late 90s.

"They were closely associated with Ranvir Sena," an official said.

Pandey was convicted and sentenced to life imprisonment for the kidnapping of a noted neuro-surgeon in Patna.