The victim, Nitin Padalkar, ended his life by jumping before a running train at Kalyan railway station in the neighbouring Thane district on Friday evening, they said.
He has allegedly named two of his college-mates for harassing him in a suicide note, police said.
Padalkar, a second-year student of electronics and telecommunications at the Ramrao Adik Institute of Technology in Navi Mumbai, was depressed for quite sometime, police sources said.
Based on the preliminary enquiry and the circumstances of the death, it is suspected that "Padalkar was a victim of ragging", police sources said.
"We will question two of his college-mates tomorrow," sources at Government Railway Police, Kalyan said.