KOLKATA: CID is still digging around for the “conspiracy” angle in the Ranaghat nun-rape case , saying that a SIM card found in the convent on Saturday buttresses the theory that outsiders carried out the horrifying crime.The state agency believes a mix of criminals from Bangladesh, Bihar and North 24-Parganas was involved and officers are probing if the gang was hired by someone with an ulterior motive. The mysterious SIM card, which was used to make calls to a neighbouring state and a country, is registered with a fake address, CID sources say.The nuns’ statements to police and the questioning of the guard at the CID HQ in Kolkata have yielded crucial leads on the languages/dialects the robbers spoke. Some investigators feel that the gang members split themselves in three groups so that each may be led by a different criminal. From what the guard and some of the people detained so far have told CID, most of the gang were Bangladeshis, say sources. This could hint at a bigger motive, claim investigators. Given the several stray incidents that took place inside the convent before the rape and robbery, investigators are trying to establish if someone had hired the criminals.CBI is sending its Special Crime Team from Delhi to take over the probe and has asked its Kolkata unit to coordinate with CBI till then. The central agency’s technical team has already started tracing calls. Sources said if CID can provide CBI any evidence of the involvement of Bangladeshis, CBI will approach Interpol for help.CID spent another day talking to the nuns. State electricity officials were summoned to ascertain if there was any power cut between 1.30am and 4 am on March 14. CID might also speak to the police patrol on duty that night. The agency is trying to ascertain the value of the convent land. Police have asked the convent for documents of the sale of 20 bigha land at over Rs 1 crore and want to know if they were planning to sell off an 80-cottah plot in the vicinity “under pressure”, say sources.