"Interrogator": "How could they say that guard's brother was involved?Since guard's brother was not part of the school or was never found anywhere.", 
"Interrogee": "As they found two or three hair in Maya's hand and when they tested that hair and matches the DNA with guard, then it matches with guard but he was in the police station. Then they match it with his brother and it exactly matched with him and that's how the police knew that guard was involved."