The former head of a Maryland-based credit card processing company is seeking more than $192 million in damages from Duane Morris, alleging that the attorney he hired to assist him in selling a controlling interest in the company failed to disclose his relationship with the buyer, a Baltimore-based venture capital firm.

Plaintiff Marc Potash, founder and former chief executive officer of SecureNet, a Maryland limited liability company, claimed in a complaint filed in the Circuit Court for Baltimore City on Monday that he had hired defendant George Nemphos, managing partner of Duane Morris’ Baltimore office and chair of the firm’s corporate practice group, in 2010 to advise him in the sale of a controlling interest in SecureNet to venture capital firm Sterling Partners.