Federal agents recently worked with one of Rod Blagojevich's closest former aides to secretly tape the Illinois governor as part of a wide-ranging probe into corruption in his administration, reports the Chicago Tribune.

Says the paper:

The cooperation of John Wyma, 42, one of the state's most influential lobbyists, is the most stunning evidence yet that Blagojevich's once-tight inner circle appears to be collapsing under the pressure of myriad pay-to-play inquiries.

Wyma has made frequent appearnaces in the scandal. Adds the Tribune:

Indeed, Wyma's and the Blagojeviches' relationship has always been both personal and professional. The governor routinely reported exchanging personal gifts and often appeared at Wyma-sponsored fundraisers where Wyma's clients hobnobbed with the governor before turning over checks for his campaign fund.

Blagojevich, who will decide on Barack Obama's replacement in the U.S. Senate, has been under federal scrutiny for over three years, but has not been formally charged with wrongdoing.