(CNN) -- Italian prosecutors will press charges against at least one person after racist abuse during a soccer game prompted AC Milan players to walk off the field in the middle of a game.
Police and stadium cameras have identified a 20-year-old man and prosecutors expect to identify more people to charges, prosecutor Mirko Monti told CNN.
AC Milan's Kevin-Prince Boateng, the main target of the abuse, kicked a ball into the stands, tore his shirt and led his team off the field Thursday in a rare protest against racist behavior by soccer fans.
Boateng was one of several black Milan players, along with M'Baye Niang, Urby Emanuelson and Sulley Muntari, who were the targets of racist abuse in the friendly against Pro Patria.
Boateng, who was visibly upset by the chanting, picked up the ball and kicked it into the crowd. After the incident, Boateng tweeted: "Shame that these things still happen... #StopRacismforever."
"We are disappointed and saddened by what has happened," Milan coach Massimiliano Allegri told reporters.
"Milan play for the right to respect all players. We need to stop these uncivilized gestures.
"We are sorry for all the other fans who came here for a beautiful day of sport.
"We promise to return, and we are sorry for the club and players of Pro Patria, but we could not make any other decision.
"I hope it can be an important signal."
Italian Football Association president Giancarlo Abete also hit out at the unsavory scenes and announced an investigation into the incident.
Abete said in a statement on the Italian FA website: "No sanction or measure can erase the disdain for an unspeakable and intolerable episode.
"We must react with force and without silence to isolate the few criminals that transformed a friendly match into an uproar that offends all of Italian football."
Boateng is not the first footballer to take a stand over racist abuse.
Former Barcelona striker Samuel Eto'o threatened to leave the field back in February 2006 after being subjected to racist abuse and pelted with bottles during a game against Real Zaragoza.
The Cameroon forward, who now plays for Anzhi Makhachkala, tried to walk off only to be persuaded to remain by then manager Frank Rijkaard.
And in 2011, Brazilian defender Roberto Carlos walked off the field after a banana was thrown at him during a Russian league game.
Carlos, who was 38 at the time, was playing for Anzhi in the city of Samara in the Caucasus region. The Brazilian is now Anzhi's team director.
After picking up the banana, Carlos walked off the field visibly upset before sitting on the bench.
This season matches across Europe have been punctuated by repeated outbursts of racism. Ahead of the European Championship finals in Poland and Ukraine, UEFA president Michel Platini had urged players to allow the referee to deal with the problem of racist abuse, and stressed that officials could stop games if necessary.
"It is a referee's job to stop the match and he is to do so if there are any problems of this kind," said Platini
However UEFA has come under criticism for the punishments it has handed out regarding racist abuse.
In December UEFA appealed the decision of its own disciplinary committee after the Serbian Football Association was fined $105,000 for improper conduct by Europe's governing body following allegations of racist abuse during the under-21 game with England.
That fine was far less than that handed out to Denmark's Nicklas Bendtner, who was forced to pay $125,800 for exposing boxer shorts with the logo of an online betting company during the European Championship Finals.
Last year, Manchester City officials were infuriated after the club was fined $40,000 by UEFA for taking to the pitch late for a Europa League game -- $13,000 more than Porto's sanction for fans' racist abuse during a game against the English team.
Milan's squad captain Massimo Ambrosini gave his backing to Boateng's actions, insisting a "message had to be sent against uncivilized people."
"I am sorry for all those who were at the stadium but a strong message had to be sent," said Ambrosini.
"AC Milan will make an effort to go back to Busto Arsizio especially for the children and for those who have nothing to do with racism but a message had to be sent against such uncivilized people."
AC Milan director Umberto Gandini added on Twitter: "Very proud of the Milan players who decided to walk off the pitch today for racist abuse from few idiots! No racism, no stupidity!"
Milan returns to league action on Sunday against Siena.
Meanwhile, World Club Cup winners Corinthians has announced it has agreed a $19.6 million deal with Milan for Brazil striker Alexandre Pato.
The 23-year-old, who joined Milan in 2007 from Internacional, scored 63 goals for the Italian giant during his five-year stint with the club.
But his career has been hampered by injuries in recent years, with the forward managing just 11 appearances last season and seven so far this campaign.
"In the coming days, Pato, who will wear the number seven shirt, will undergo a medical and then sign a four-year contract," said a club statement.
Milan confirmed the deal on its official website: "AC Milan can announce that Alexandre Pato has been sold outright to Sporting Club Corinthians Paulista."
In an open letter on the club's website, Pato said: "I wish to salute and especially thank everyone. From the president to the many people I worked with in these unforgettable years at Milan.
"I am going to Brazil, to Corinthians, so I'll have the opportunity to play consistently. It will not, however, be easy to forget Milan.
"I will always be tied to this jersey, the club colors and all the Rossoneri fans. Above all at this moment my thoughts and my biggest thanks go to them."
Iona Serrapica contributed to this report.