inputs: hypothesis: Philip Markoff is a medicine student at the Boston University School of Medicine. premise: (CBS) The world knows Philip Markoff only by his headline nickname, the "Craigslist killer," but to Morgan Houston, he is more than a suspect or a defendant. To her, Markoff was a classmate and a friend - someone she thought she knew. "I thought he was very nice," she tells 48 Hours Mystery correspondent Richard Schlesinger. "He was dorky, but so many of us are. I mean, I can be a big dork, too. So, you can't hold that against him." Houston first heard that her college friend had been arrested from another friend on the social networking Web site, Facebook.