knows what he's doing. >> only charlie tan wasn't at all okay. it snowed that night, a muffling blanket, covering the home where something awful was about to happen. >>> why did charlie need to rush home? the first clue coming from a friend's mom who called 911. >>> coming up -- >> he didn't give us a lot of details. i'm just worried that he might do something at his house. >>> when "dateline" continues. the moment you realize you're ready to make dinner but your oven isn't. at lowe's, we have more appliances to choose from. so, you can get the right one, at the right price, right now. get up to 35% off select appliance special values at lowe's. >>> this is their way of showing they don't accept their claim to jerusalem. >>> when charlie tan left cornell and made the trip home on a thursday winter morn, his football coach knew he had been upset. >> i asked him to call me when he got home >> and that very evening in pittsford, new york, charlie spent time at a friend's house where he seemed despondent, sad, possibly depressed. not the charlie he'd

. >> charlie tan told police he shot his father to save s mother. but investigators were finding flaws in that story. the ivy league student had been arrested and was facing second-degree murder charges. was this an intentional killing or justifiable homicide? here again is dennis murphy with "house of secrets." >> anna valentine was in a state of disbelief when she learned that her close friend charlie tan had been arrested. >> did you have a chance to talk to charlie himself in that period? >> he called me on the phone a couple times from jail. >> anna didn't sit around.