I know what you did while you were in college

It happened on Christmas Eve last year, I got a message from an unregistered number saying that she’s my classmate Ruby Jean and she got my number from another classmate. She asked how I was and the usual blah blahs but there’s something about her message that doesn’t ring true so I verified with my other classmates about her number. It turned out that it’s not Ruby Jean’s number, so I texted the number and said to prove to me that she really is my classmate. She then called me up and I don’t recognize the voice. When I told her she doesn’t sound like the Ruby Jean I know, she said that she has a cough and that she was using her husband’s number. She knew the names of my classmates and seems really anxious to know our whereabouts but it just feels weird coz she got some details wrong like who worked where and who got married. Anyways, I called up the real Ruby Jean and she said she have no idea who the prank caller is. I called up the number again and the same voice answered but this time she claimed that she didn’t call or know me. Anyways, I got busy and forgot about it when a week later another classmate got the call from somebody claiming that she’s Ruby Jean again. It was the same number. I changed phone numbers after that and heard nothing about the prank calls from my other classmates. But just last Wednesday, the prank caller strikes back. She contacted two of my classmates and now claims that she’s Agnes and she’s asking for info about our classmates. Another unregistered number is also threatening one of my classmate and we suspect it’s the same person. When a friend of Agnes called her up, she claimed that she’s Agnes and was able to answer the info about Agnes correctly. My friend Agnes is really bothered by this and doesn’t know how to deal with it. All of my classmates are truly mystified by this and wanted to unravel who the caller is but we are clueless on how to do it. Coz the number is pre-paid and even if it is post-paid/plan I’m not sure the network would divulge any info. We don’t know what the prank caller really wants. I feel like I’m in an “I know what you did last summer” kind of movie hehehe Maybe it’s a vengeful teacher whom we didn’t listen to while in college or a classmate whom we labeled as loser, the kind that nobody bothers to talk to or befriend but nah we weren’t that cruel. I can’t simply understand why some people would do this kind of thing and what can they get out of it. The Nancy Drew in me wanted to solve this mystery and the psycho in me just can’t accept that there are patients out there sicker than me