A day after the baby-swapping case ended on a happy note with the baby boy being handed over to his mother, the police today arrested four persons, including three employees of the government maternity hospital, for their alleged involvement in the case.Three staff members of Nayapul Maternity Hospital ??? Surendra Raju, Suryakala and Vijaya Mary - and Shaik Naseer, husband of Mahmooda Begum, from