(ANSA) - Cremona, December 17 - Italian prosecutors said Tuesday that they are looking at around 30 suspect matches in Serie A as part of new developments in a massive match-fixing investigation. Early on Tuesday police arrested four people in relation to the probe and it emerged that investigators have put around 20 people under investigation. The people being probed include former AC Milan and Italy midfielder Gennaro Gattuso, a member of the Azzurri's 2006 World Cup-winning team, and former Milan and Lazio player Cristian Brocchi. They are suspected of criminal association and sporting fraud, judicial sources said.