How to catch a cracker in the US?

Hi, I'm an ISP in Germany and a cracker (not a hacker :) ) has targeted a customers of mine in the last days. The cracker was successful and caused financial damage / was successful with data theft. I set a trap and finally caught his real IP address - a Comcast user in the US (100% not a proxy or bot). What would be the next steps to pursuit him? If I contact local authorities here in Germany I'm afraid months will pass by and Comcast will have possible already deleted their logs by then (?). Any advice? Thank you! Markus