An ABVP activist, suspected to be involved in the death of Professor HS Sabharwal, on Friday surrendered before the Madhya Pradesh CID which is probing the case, police said.
Vishal Rajoria, who along with three others, was identified as an accused in the case by CID, had been absconding since the murder.
Other three accused were arrested on September 20 from Ujjain, while Rajoria surrendered on Friday following intense pressure by the police.
Meanwhile, a local court on Thursday remanded the three arrested to five days' police custody.
With Rajoria's surrender, the total number of arrests in the case went up to six.
Professor Sabharwal was allegedly manhandled by unruly students on August 26 after the cancellation of the college union polls in view of the allegations of irregularities.
Others arrested in the case were ABVP former state president Shashiranjan Singh Akela, former secretary Vimal Tomar, ABVP workers Hemant Dubey, Sudhir Yadav and Pankaj Mishra.