Apparently I'm wrong. Wikileaks had some cables talking about how Martinelli asked the US to spy for him, but they denied him[1]. He did however, end banking secrecy for Panama/US in 2011(?), with a tax treaty. I probably misunderstood after reading some expat sites and connecting lines that perhaps are not connected.

http://www.cato.org/blog/wikileaks-cable-martinelli-threat-r...