Shibir is the student affiliate of the Jamaat-e-Islami.
The case's investigation officer, sub-inspector Md Kamruzzaman submitted chargesheets of the three cases concerning the explosions at the court of Chittagong's Chief Metropolitan Magistrate on Thursday.
Shibir's central student welfares secretary Mashrur Hosain and 12 others have been accused in the three cases, court police's Assistant Commissioner Nirmalendu Bikash Chakravarty told bdnews24.com.
On March 28 last year, 14-year-old schoolgirl Antu Barua was severely injured when Shibir activist lobbed crude bombs from a procession at the port city’s Hemsen lane.
Barua's right eye was damaged.
The Arpacharan City Corporation Girls' High School's ninth grade student was on her way to a private tutor when the explosion hit her.