One of the law firms involved in the scheme, Jenkens & Gilchrist, disbanded three years ago after it admitted its part in a number of fraudulent tax schemes that involved over US $1 billion in false deductions.

Chicago attorney and accountant John Ohle was found guilty of wire and tax fraud conspiracy and two counts of tax evasion. He faces a maximum of five years jail for each charge.

William Bradley, a Louisiana based lawyer, was found guilty of wire and tax fraud conspiracy for being part of a scheme that included Ohle to fraudulently obtain fees from tax shelters sold by the bank. He faces a maximum sentence of five years.

Both men are due for sentencing in early September.

Ohle was a supervisor with Bank One's "Innovative Strategies Group" which advised tax shelter strategies for high net worth clients. Ohle and others within the group hired attorneys from Jenkens & Gilchrist to help design, market and implement the strategy.

Bradley was convicted for helping to create false invoices to obtain referral fees for himself in the vicinity of $25,000. Ohle received over $800,000 of fraudulent referral fees.

Prosecutors alleged that Ohle conspired with lawyers at Jenkens & Gilchrist between 2001 to 2004 to market a tax shelter, dubbed "Homer", to help wealthy clients reduce or eliminate their income tax fees.

The high net-worth individuals were clients of both Bank One and Jenkens & Gilchrist.

The Homer transactions resulted in over $530 million being falsely claimed in tax losses and evasion, with Jenkens & Gilchrist earning over $12 million in fees as a result of this scheme.

This case follows a similar allegation of tax fraud being brought against the firm last year.

In 2009, the former head of the Chicago office of Jenkens & Gilchrist, Paul Daugerdas, was charged with matters relating to the creation of fraudulent tax shelters between 1994 to 2004. It was alleged that between 1998 to 2002, Daugerdas earned around $96 million for helping to market the shelters.

The firm paid $81.6 million to clients in 2005 who had sued it over its tax shelter advice.

Jenkens & Gilchrist itself escaped prosecution when it admitted in March 2007 that it had developed and marketed tax shelters that claimed more than $1 billion in false losses. The firm, which also had an office in Dallas, shut-down shortly afterwards.