Kuligowski said Monday that he had considered the move as a way to advance professionally and eventually be a head coach.
The Illini fired defensive line coach Greg Colby in early January. The open job was posted as a potential co-defensive coordinator to work with current coordinator Tim Banks.
Illinois spokesman Kent Brown said the search to fill that vacancy and coach Tim Beckman could name his new assistant ''at any time.''
Missouri spokesman Chad Moller did not immediately return a call regarding Kuligowski's decision to stay. Kuligowski has been at Missouri for 14 seasons.