There is no twist to the end because this is not an ending.  It is a conclusion.  Nothing was resolved, no main character, no crisis, no problem to solve, no structure.  It is a bunch of people sitting and talking about life and their neighborhood and then a shot of the serial killer who "just happened" to be at the same barbecue.

It's a story about nothing and then, just for kicks, a shot of someone who leads to nothing.

A short is supposed to have a beginning, a middle and an ENDING.

That is the main problem with this.  Needs to be re-written, simplified and restructured.

Also, LARGE COLONIAL is not part of a proper slug.  It should read something like:

EXT.  HOUSE - DAY

(the description of the house here)

and then a minislug of the backyard.

Also, a lot of passive writing, punctuation and spelling mistakes.

Thanks for writing, good attempt but try again.