. >> the college track star, dating a master panmanipulator, stalking her, breaking it off with him turned out to be the breaking point >> then she just started saying no, no, no, no, like someone might have been grabbing her or something. >> lauren mccluskey on the phone with her mother when he went on the attack. >> you were trying to save your daughter's life in that moment. >> absolutely. >> for the first time, her parents opening up to amy robach about the final moments of lauren's life. after 20 calls to police, the system they say failed their daughter. >> was her death breathable? >> yes. >> we'll be right back. ack. >>> this is a special edition of "nightline." the calls for help. now reporting amy robach. >> hi, so i'm dealing with a a situation where i'm being blackmailed for money. >> reporter: in the last days of her life, lauren mccluskey was begging to be heard. >> i think they're trying to lure me somewhere. >> do you know when an arrest would be made? >> reporter: talking with police over 20 times, crying for help with her ex-boyfriend, a seasoned manipulator who had his s

. >> the college track star, dating a master panmanipulator, stalking her, breaking it off with him turnedccluskey on the phone with her mother when he went on the attack. >> you were trying to save your daughter's life in that moment. >> absolutely. >> for the first time, her parents