Shamsuddin told the police that it was a seven-member squad that carried out the attack on Prof Joseph.
This is for the first time that someone who allegedly took part in the assault is being arrested. Shamsuddin, who hails from Perumbavoor was arrested from Palakkad according to police sources.
According to the police, Shamsuddin is involved in several attacks carried out by the Popular Front of India.
The right hand of Joseph, a Malayalam professor at Newman"s College Thodupuzha, was chopped by a group of people on Sunday, Jul 4 for preparing a question paper having derogatory references to Prophet Mohammed.