At the March 28 hearing, lawmakers are also likely to question several other former MF Global employees, who are expected to appear voluntarily. The witness list is still being finalized. The hearing is the latest in a series of congressional efforts to grill former senior managers of MF Global. http://www.reuters.com/article/2012/03/21/us-mfglobal-obrien-idUSBRE82K1DR20120321