Criminal cases had been filed against two students, including a girl, based on a complaint from the parents of the deceased, police sources said.
The body of the second year engineering student was found on the railway track, 15 km from Devanahalli on the city outskirts yesterday morning.
The student had left behind a suicide note stating that nobody was responsible for his death but added he was 'troubled' by college authorities and a former girlfriend, police said.
They said the boy's parents suspect it to be a case of murder. "We are still awaiting the post mortem report of the student. Only after we get the report, we will be able to throw some light whether it was suicide or murder."