A second city contractor is now cooperating with a federal investigation into allegations of bribery at Atlanta City Hall after he pleaded guilty to a single conspiracy count Thursday.

But federal charging documents for contractor Charles P. Richards Jr., owner of C.P. Richards Construction Co. and C.P. Richards & Associates, and city contractor Elvin R. Mitchell Jr.—who pleaded guilty to a single bribery conspiracy count last month—still have not revealed to whom the bribes were paid and for whom they were intended.