Former RPF constable Chetan Singh Chaudhary, who killed four with his service weapon onboard Jaipur-Mumbai Central Superfast Express in July, is mentally stable, Government Railway Police (GRP) said in its chargesheet. Chetan was aware of what he was doing, GRP added. GRP filed over 1,000 pages long chargesheet and stated that it relied on the depositions of over 150 witnesses.