Okay, here is what I recall of the book:

It is a true crime novel about a farm-type family that gets killed really brutually (Massacre might be in the title of the book) by a couple (I'm pretty sure it's more than 1) if guys.

The author is a very famous author however I don't think he normally writes true crime type books.

Any help is much appreciated!

I'll try and think of some more things about it...

I'm sure that I will know it immediately if someone posts it

"In Cold Blood" by Truman Capote?

My first thought was In Cold Blood by Capote. But if you mean a guy and girl couple there are several books about Charles Starkweather and Caril Ann Fugate who went on a murder spree in the 50's. A movie was made based on them by Terrence Malick called Badlands with Martin Sheen and Sissy Spacek. The book I read was called Wasteland.

Thanks for the responses...that is right...it was Truman Capote's book...thanks for jogging my memory! :)