Police have launched an official investigation into the recent network hacking incident at the country’s largest mobile carrier, SK Telecom.

The cyber investigation division of the Seoul Metropolitan Police Agency said Wednesday that it has shifted from an internal probe to an official investigation. 

It added that the division chief will lead a 22-member team dedicated to the case. 

Police said they are investigating the circumstances of the hacking incident and working to determine who is responsible, while swiftly securing digital evidence and activating domestic and international cooperation systems. 

They vowed a thorough, systematic investigation in light of the significant public interest in the case and the anxiety it has generated.