I lost a hatchling corn snake about a month and a half ago and still haven't found her. One person told me he/she lost a snake for two years and eventually found it in the basement! I tried every trick you can possibly think of to no avail. I really really hope you find your snake because I know how bad it sux to lose one. Anyway, here's what I tried:
*I put plastic wal-mart bags behind the couches and other hard-to-easily-reach areas so if she was slithering back there, she'd make the bags rustle.
*I put flour in all the doorways
*I blacked out a 16oz coke bottle with a black sharpie, put it on a heating pad set on low, and put a water bowl nearby
*I ended up also putting a pinkie in the coke bottle overnight
*I looked under the fridge, under the TV, under the Xbox360, near the PC, etc.
*I also put flour around my little "coke bottle" setup
Even though none of this worked for me, maybe it will work for you. Like I said, I hope you find him and I hope your family comes to their senses. No point in killing something just because you're afraid of it.