After some intelligent tracking and investigation based on mobile phone call records, the West Bengal police on Thursday made the first breakthrough in the Ranaghat nun gang rape case by arresting a possible suspect from Mumbai. The suspect, Mohammad Selim, is being flown back to Kolkata.

 With this arrest the police may be able to pin down other culprits. The breakthrough reportedly came after some dogged Call Detail Analysis after the school principal Sister Shanti told the CID officers that the miscreants had used a cell-phone and were seen speaking over it.

Selim is believed to be among the seven-eight suspects who had been part of the three-and-a-half hour operation in Ranaghat's Jesus and Mary Convent on the wee hours of March 14. The septuagenarian Christian convent teacher was allegedly gangraped after she tried to prevent a robbery attempt by them. The elderly nun was admitted to a hospital in Ranaghat and was later discharged on March 20. The gang had taken away about Rs. 2 lakh from the office cupboard and some valuables from the chapel.

The Mamata Banerjee government had entrusted probe to the state CID (criminal investigation department) of police. However, a political fallout and subsequent lack of progress forced the chief minister to hand over the probe to CBI. However, the CBI is yet to formally take over the case.

The CID had been in a statewide hunt and had detained as many as 15 people. Four of the assailants had been captured in the convent's CCTV footage, later made public.