The student was killed on September 8 allegedly by a senior student. (File) New Delhi: After nearly three years of probe, the Central Bureau of Investigation (CBI) has filed a charge sheet against four police officials of Haryana for allegedly framing a bus conductor in the killing of a seven-year-old student of a private school in Gurugram in September 2017, officials said on Friday. The student was killed on September 8 allegedly by a senior student. The CBI filed its supplementary charge sheet in the case, commonly known as the Ryan murder case, before a special CBI court in Panchkula against the then SHO of Bhondsi police station Narender Singh Khatana, Sub-Inspector Shamsher Singh, ASI Subhash Chand and ACP (Sohna) Barem Singh.