The story specifically says Sam's friend Charlie contacted campus security after Sam stopped responding to Charlie and Kayla (Sam's girlfriend). Campus security wouldn't have known to check in within a day if Sam's friends weren't on top of keeping in touch with him. (Put another way, I certainly would've rotted longer than that if this had happened to me in college-- lucked into having my own dorm room & had acquaintances but not any friends who would've gone out of their way like that.)