I love hearsay. It's a dirty, shameful secret of mine but I love kicking back and researching these horror mysteries. Some come from watching the movie a couple times and some come from straight from yon interwebz. I present the THIRD KILLER THEORY IN SCREAM (1996)!!!!!!!!!!1!!!!!!!!!! ZOMFG!!!!
Um, anyway... In the brief (and I do mean brief) interlude between Scream (1996) and Scream 2 (1998) there was some speculation that there would have had to have been a third killer if we believe everything that the characters relate to us. There are a couple theories I've heard... the Dewey (David Arquette) theory but my money's on Tatum (Rose McGowan) as the third killer. Now pull up your computer chairs to the warm, warming glow of your monitor and let me blow your mind.
We all go a little made sometimes. The killing of Casey (Drew Barrymore) at the beginning is problematic. You would need at least two killers to pull that off but a scant few scenes later Stu (Matthew Lillard) says it couldn't have been him because he was with Tatum all night. Stu is accused of Casey's murder because they used to date. A little vengeance with a side of jealousy makes sense, non? Even if Tatum didn't actually kill Casey, the alibi is pretty damming.
If Tatum at the very least aided Billy and Stu in their killings, then her death makes sense. If Billy and Stu are the lone killers it doesn't really make sense as to why they would kill her. You could argue that they were ridding Sydney (Neve Campbell) of her allies but it's a pretty wishy-washy motive, especially for a series of killings that seem to be so heavily motivated by one past transgression. Tatum's death can read as Billy and Stu covering their tracks. Perhaps they don't really trust her. Perhaps they wanted all the glory.Who knows? There are few certainties in the hypothetical .
I will say though that the Dewey theory is interesting and would have been pretty mind-blowing if they'd manage to incorporate that into the second movie. It would have been a very Norman Bates moment to have the mild-mannered local sheriff turn into a criminal master mind who'd been playing them all off each other. Like a pinball machine. But with more knives.