* "Hard to envision" Peregrine CEO acted alone-son's lawyer

* NFA president also raised possibility CEO had accomplice

* Son, president of failed firm, puts Iowa home up for sale

By Tom Polansek

CHICAGO, July 26 (Reuters) - Peregrine Financial Group's Chief Executive Russell Wasendorf Sr. likely had an accomplice to help carry out an alleged 20-year fraud, contrary to his claim that he acted alone, the lawyer for Wasendorf's son said on Thursday.

Nicholas Iavarone, who represented Peregrine in legal matters for two decades before its collapse this month, said it was "hard to envision" that Wasendorf Sr. had pulled off the scam "without some type of assistance." Iavarone reiterated that Russell Wasendorf Jr., who was president and chief operating officer of the failed futures brokerage, knew nothing of the fraud.

Peregrine, commonly known as PFGBest, filed for bankruptcy protection on July 10, a day after Wasendorf Sr. attempted suicide and left a note describing how he had bilked customers of more than $100 million over nearly 20 years. He said he had forged bank statements and intercepted mail between U.S. Bank and the firm's auditors at the National Futures Association.

He said in the note that he had concealed his crime "by being the sole individual" at Peregrine with access to statements from accounts at U.S. Bank and by telling bank employees that he was the only Peregrine employee they should contact.

The possibility of wider involvement was raised publicly a day ago by Daniel Roth, president of the National Futures Association.

Iavarone said it would be logical for Wasendorf Sr. to have had some assistance within the banking or auditing sectors outside Peregrine.

A spokesman for the National Futures Association declined to comment. U.S. Bank said its employees had done nothing wrong.

The public defender representing Wasendorf Sr. did not return a call for comment.

Wasendorf Sr., who is in jail, was arrested on July 13 for lying to regulators. He has waived his right to a preliminary hearing in his criminal case, which was scheduled for Friday.

A spokeswoman for the Federal Bureau of Investigation, which is investigating the case, said it was "covering any possible angle."

Wasendorf Jr. has been cooperating with investigators and has not been told that he is a target, Iavarone said. Still, the lawyer said he was "sure that everyone is looking at him and the other officers of the company."

Wasendorf Jr. is trying to sell his house in Cedar Falls, Iowa, where Peregrine had its headquarters, to pay legal fees and support his family, Iavarone said. (Reporting by Tom Polansek)