OK, I am beyond desperate! I have been trying to track this book down for years - I've asked almost everyone I know, I've spent hours online trying to find it, I've posted in various forums and I keep hitting a dead end. If anyone is able to help me I can't even tell you the joy it will bring me. 

The book I'm looking for is from the 90s, possibly the very late 80s, but I'm pretty sure the early 90s. It's a thriller and what I can remember from the story concerns a young girl who becomes suspicious of an older man in town (he may be her neighbor). I think that there is a serial killer on the loose and our heroine comes to believe it is him but I could be wrong on this detail. Someone is up to something no good at any rate and she is convinced it is him. Anyway, this guy lives by himself and every year for Halloween carves a bunch of Jack o' Lanterns and puts outside his house. At the end of the book I believe it is revealed he does this to honor his late wife. Of course it also turns out that this man is not the culprit of any nefarious deeds and even ends up saving the heroine from the villain, a showdown that takes place on his pumpkin filled porch. It has been a very, very long time since I read this and my memory is probably not 100% - there is a good chance some of the plot I may have gotten completely wrong or mixed up, but that is the general gist of it.

The thing I remember most about this book is the cover, it show the heroine (I believe glimpsed through a window or looking in the window of a darkened house) and all around her she is surrounded by the blazing Jack o' Lanterns. Again, it's been a while since I have seen the cover so some of this may be slightly off. 

If anyone can help me with this, or has any idea of what book I might be talking about or who wrote it I will be eternally, forever, massively grateful. I've been trying to find this for so long that I'm starting to think I just completely imagined it. It would make be so happy to be able to find it. Thank you for taking the time to read this and thank you to anyone who tries to help! 

nope sorry, not ringing a bell...  sounds like something Christopher Pike would have written though..

Thanks for the reply! Unfortunately it is not Christopher Pike, I think the age this was marketed to was more tweens than teens.