By Elise Viebeck - 05/02/12 12:58 PM EDT
He also called on the Centers for Medicare and Medicaid Services to investigate.
Franken, meanwhile, wrote to Accretive founder and CEO Mary Tolan demanding answers to a series of questions.
"Did Accretive employees in any way suggest to patients that they would not receive treatment if they could not pay for it or if they could not pay a past debt?" one question read.
Franken asked the firm to respond by Friday, May 4.
According to a Tribune photo caption, Chicago Mayor Rahm Emanuel visited the company's headquarters there on Tuesday and met with Tolan.