India, Feb. 7 -- What are the chances of identifying someone you're looking for in a Mumbai local train? Even though the odds were heavily stacked against them, police officers of the Government Railway Police (GRP) boarded the 5.10pm Borivali-bound train at Andheri station, determined to find witnesses to the January 24 murder at Malad station.

They found not one, but three witnesses to the incident, which claimed the life of Alok Singh, a 33-year-old NM College teacher stabbed to death after a petty quarrel over right of way in a train compartment.

Singh, who had boarded the 5.10pm train at Andheri, was lined up near the door, waiting to alight at Malad. As the train pulled in at Malad, 27-year-old Omkar Shinde, who worked in a jewell...