Nikhil was later produced in court and remanded to 6 days' police custody.
After interrogation in police custody, Nikhil confessed about having fired two rounds at his wife near Law institute compound, Kalyani on Thursday night, the officer said.
Another person Basudeb Sen, detained by the police, was released by the police after Nikhil's conferssion.
23-year-old Moumita Biswas, a first year student of S K Acharjee Institute of Law in Kalyani, was found lying in pool of blood with bullet marks on her head after leaving her Khardah home on Thursday afternoon.
The SP said police would now procure the missing weapon used to commit the crime.