More than two months after rape and murder of Nirmala Panta, Nepal Police has not been able to identify the culprits and arrest them. Instead, very investigation process, including the DNA tests of suspects, has come under question. Where did this process go wrong? How should such investigations be handled? Professor Dr Harihar Wasti, Chief Consultant at Forensic Medicine Department, explained various steps of forensic and post-mortem investigation process in an interview with Mahabir Paudyal and Thira L Bhusal. Edited excerpts: