The Tom Petters saga continues: Bankruptcy trustee Doug Kelley has reportedly sued Chicago-based BMO Harris Bank, which acquired M&I Bank last year, and is accusing the company of “aiding and abetting” Petters’ $3.65 billion Ponzi scheme by ignoring huge deposits.

M&I Bank, formerly based in Milwaukee, was allegedly aware of the fraud but turned a blind eye to the source of funds moving in and out of a bank account used by Petters Companies, Inc., to finance the fraud scheme, according to a report by the Star Tribune.

BMO spokesman Jim Kappel told the Minneapolis newspaper that the claims are “completely without merit,” and the bank plans to vigorously defend itself.

The lawsuit reportedly claims that between 2003 and 2008, more than $35 billion was deposited into the M&I account controlled by Petters Companies, and none of it came from the retailers with which Petters was purportedly conducting business.

The lawsuit seeks unspecified damages, calls the account’s deposits “astronomical,” and states that M&I was never given “a valid business reason for such a staggering amount,” according to the Star Tribune.

Petters, who was once one of Minnesota’s most promising entrepreneurial success stories, was sentenced in 2010 to 50 years in prison for orchestrating a Ponzi scheme. After more than three years of silence, he spoke earlier this year with Twin Cities Business Editor in Chief Dale Kurschner; to read the resulting story, click here.