A total of 11 educational institutions suspected of leaking test sheets for China's postgraduate entrance examination were shut down after a 4-month investigation by police in Central China's Hubei Province. Some test sheets were reportedly even transmitted from the printing plant via slingshot, China Central Television reported on Monday.

Around 90 minutes before the English examination on December 26, 2015 - the first day of the 2016 national postgraduate entrance examination - a handwritten English question sheet went viral on social networks.

The questions turned out to be exactly the same as those on the real examination, causing a tremendous stir among the public.

Police in Jingzhou, Hubei immediately launched an investigation of the leak and caught a suspect surnamed Wang, the head of an educational institution, as he was transmitting exam answers via radio.

Tracing backward from Wang, the police found more suspects. Two suspects surnamed Li and Luo were found to be the initiators of the leak, which had been planned since July 2014.

Luo formerly worked in a printing house that printed college and postgraduate entrance examination papers in Henan Province.

Luo used slingshot-like device to transmit photos of test sheets to Li on December 15, 2015.

They then cooperated with 11 educational institutions across the country to disseminate the images.

The 11 institutions involved in the cheating scheme were  ultimately shut down.

It is the first case of "organizing cheating in an exam" since an amendment to the country's Criminal Law took effect in November 2015, stipulating that those found guilty of organizing or facilitating cheating or hiring others to sit exams  could be imprisoned for up to seven years.