Check out this interactive post from MusicScore.com where you can listen to, read and download the sheet music for the Law and Order: Criminal Intent theme.
You can buy a two-page digital copy of the Law and Order piano sheet music and a digital copy of the theme music for Alto Sax. Both sites offer the first page free of charge so you can decide if you want to buy it first.
There are lots of videos on youtube that will show you how to play the Law and Order theme on different instruments. Do a quick search and you'll find videos like these below, one is piano and the other is blues guitar.
