The Railway Protection Force on Tuesday arrested the man who allegedly molested an 18-yearold girl on a moving train on Monday. The accused, identified as Pandiya Ramlingam, hails from Tamil Nadu and had arrived in the city a week ago.Ramlingam, 20, was picked up from platform no. 1 at Churchgate, where he had allegedly groped the college student and jumped off the train after she raised an alarm. While he was identified by the girl and confessed to the crime, the police said he appeared mentally unstable.Based on the statement of the victim, the police had a hunch that molester would strike again. They kept a vigil at Churchgate. According to an RPF official involved in the investigation, Ramlingam reached the station around 6 am and began loitering on the platform.“He then stood in front of a ladies compartment staring at a college going girl on the train. He was arrested while trying to board another ladies compartment of the same train,” said the official.Recounting the horror to Mirror, the 18-year-old said, “I was listening to music and as the train began to move, he hopped into the compartment. Startled that a man had entered the coach, I turned off the music and was on guard. He started walking towards me making obscene gestures. I asked him what he wanted, but he didn’t stop.” She said the molester jumped off near Wankhede stadium, minutes before the train reached Marine Lines station.Senior divisional commissioner of RPF on Western Railway, Anand Vijay Jha said, “It is difficult to catch such people as we have observed in the last four cases that the criminals board a moving train during off-peak hours.”