Samandar was arrested last Saturday by the NIA from Nagda in Ujjain district of Madhya Pradesh.
NIA officials are tight lipped on the interrogation of Samandar. Sources told HT that he may have killed Joshi who had boasted of leading the group of right-wing extremists that carried out a series of bomb blasts in Malegaon (September 2006), Samjhauta Express (February 2007), Mecca Masjid (May 2008), Dargah Ajmer Sharif (October 2007) and simultaneous blasts at Malegaon and Modasa in September 2008.
"Joshi was boasting too much about successes of the group after the Ajmer Sharif blast. His co-conspirators were feeling insecure. He had also mediated with local feuds in Dewas (MP) to generate money. He wanted to open a liquor shop and was also dabbling in commodities exchange. Witnesses have already indicated that Samandar may have murdered Joshi," said a source.
Investigators say Samandar may have been involved in many murders in Mhow. He has confessed to his involvement in Samjhauta blast, Mecca Masjid blasts and Malegaon blast of 2006, said sources.
"There have been a few instances of bike riders getting shot in a similar manner in which Joshi was also murdered. These murders took place in and around Mhow. The NIA will have to join dots before a conclusion can be drawn. A mere confession of Samandar in this regard will not stand in court," said a senior home ministry official.