In litigation stemming from a $23 million Ponzi scheme run by a Chester County man, a federal judge has refused to dismiss negligence claims against a Delaware accounting firm that is accused of ignoring signs of fraud when it audited the Acorn Capital Management investment firm.

In the suit, court-appointed receiver Louis C. Bechtle contends that the Ponzi scheme run by Donald Young should have been detected in the 2003 audit conducted by Master Sidlow & Associates of Wilmington, Del.