NEW DELHI: The Central Bureau of Investigation has initiated a probe in the anti-sterlite clashes between demonstrators and police that left 13 people dead and over 40 injured in Tamil Nadu's Thoothukudi in May this year. CBI recorded statements of families of the people killed or injured in the firing. The investigating agency also summoned several documents from the state police including documents on whose order 15 weapons were issued, who had signed and collected the weapons and who ordered firing that led to the killings. The Madurai Bench of Madras High Court transferred all cases pertaining to the violence and police firing to CBI, back in August. Justices CT Selvam and Basheer Ahamed also quashed the detention of six members of Makkal Adhikaram. The members were detained under the National Security Act, 1980.