Twenty days after the daylight murder of 21-year-old engineering student Monica Kirnapure in the city,the Nagpur police have claimed to have cracked the case and arrested a youth from a local slum. And shockingly,initial probe has established it to be a case of mistaken identity. The police arrested Shrikant Sonekar,a member of the gang of contract killers that stabbed Monica several times with a dagger in full public view on March 11 when she was heading for her SRM College of Engineering here,on Thursday. Sonekar has unravelled the entire plot and it is surmised now that they had been given the job of killing another girl of the college,who,incidentally,was Monicas friend,but ended up killing Monica instead, senior police officials said on Friday. The two girls had similar personalities,a reason for killers mistaking the identity of their target, the officials said. The police had deputed a few women police officers,one of them specially called from Chandrapur,at the college hostel from where some information kept trickling. The police had also simultaneously got a cyber expert police officer to track thousands of calls that originated or terminated in the local mobile towers range. There were about one lakh such calls serviced by 13 companies. But we had got some information from our sleuths in the hostel that one of the girls had been talking frequently to a youth on mobile. We concentrated on her calls and tracked the youth,who was brought to Nandanwan police station for interrogation. The girl was also interrogated. They,however,didnt reveal anything clinching,but agreed that they had been in touch, a senior police officer said. The calls revealed that the youth often asked the girl about another girl,as regards her time of going to college and the road taken,etc, he added. It was this another girl who was his target. He apparently had befriended the girl but the girl had later parted ways,which angered him. The girl also conceded she once had friendship with Kunal. An angry Kunal gave a contract to a gang from Narkhed to kill her. One of the four gang members,Pradeep,knew which girl had to be killed. But as it turned out,he failed to identify her and they ended up killing a wrong target, he further said. Police on Friday arrested Kunal and Pradeep. The three accused have been remanded in police custody till April 7. The police are on the hunt for two others.