The incident occurred in Vallanadu of Tuticorin district, about 650 km from Chennai.
All the three student attackers have been nabbed, police added.
Principal of the Infant Jesus College of Engineering and Technology L.R.D. Suresh, 53, was fatally attacked for suspending a fourth year student, P. Pichaikannan, a few days back.
Action against Pichaikannan was initiated following an internal college inquiry that found him guilty of a violent act in a private bus.
Upset at his suspension, Pichaikannan and his two friends, fourth year student G. Dannis and third year student M. Prabhakaran, of the same college attacked Suresh with sharp weapons in the morning and ran away.
Other faculty members and students rushed Suresh to a hospital. However, doctors declared him dead and the body was sent for post-mortem examination.
Last year, a Class 9 student of St. Mary's Anglo-Indian School here stabbed his Hindi teacher, Uma Maheswari, to death for complaining to his parents about his poor academic performance.
--IANS (Posted on 10-10-2013)