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When Wells Fargo's (NYSE:WFC) Chairman and CEO John Stumpf testified before Congress last month about the bank's fake-account scandal, the possibility was raised that the fraud began as far back as 2007 -- four years before the bank has admitted to.

But now there's reason to believe that it went back even further. The New York Times published a piece today quoting former employees of the bank who started reporting the scam to supervisors, the human resources department, and the bank's ethics hotline as early as 2005.

This got me thinking: Maybe the fraud actually dates back to 1998. That was the year Wells Fargo merged with the Minneapolis-based Norwest Bank and handed the reins over to Norwest CEO Dick Kovacevich and his understudy Stumpf.

It was Kovacevich who pushed the combined banks so hard to cross-sell financial services. Here he is writing in the combined banks' 1998 letter to shareholders:

Over the past 10 years, Norwest built a reputation for having the industry's strongest sales and service culture.

He then goes on to say that:

We intend to propagate effective technology -- and a superior sales and service culture -- across the entire new Wells Fargo. We expect every Wells Fargo business to refer all their customers to other businesses. We want to earn nothing short of all the business of every creditworthy customer. We expect to sell at least one more product to every customer every year.

Kovacevich then conditioned those under him, as well as analysts and commentators outside the bank, to focus maniacally on the bank's cross-sell ratio -- the number of financial products (checking accounts, savings accounts, credit cards, mortgages, etc.) that its average customer used. He even stopped referring to the bank's locations as branches, preferring "stores" instead.

However, the most revealing part of that shareholder letter was an anecdote about one of its top-selling bankers. The employee had only one year's worth of experience in a Wells Fargo store. Yet, according to Kovacevich, she already ranked as "one of our best in key measures of sales performance among thousands of her peers in our 21 banking states."

What's strange is that she was based in Billings, Montana -- Norwest's traditional stomping grounds. I spent a lot of time in that area growing up and love it, but in terms of the demand for banking products, it would pale in comparison to Los Angeles or San Francisco, Wells Fargo strongholds.

It's worth asking, then, how a banker in Billings outperformed her colleagues in two of the nation's biggest cities. Maybe she was genuinely an outlier. But maybe not. I mean, after all, she did have only one year's worth of experience in a branch. And it seems unlikely that she brought a huge book of business to the job, as the previous four years she had worked in a Norwest call center.

In 1998, the average customer at the combined banks used 3.2 products. Fast-forward to the end of the most recent quarter, and that had grown to 6.27 products per customer. And, mind you, that's after Wells Fargo's cross-sell ratio declined following its 2008 acquisition of its larger rival Wachovia.

Wells Fargo's goal was to increase this number to eight products per customer. With eight? Here's Kovacevich's successor, Stumpf, writing in the bank's 2010 shareholder letter:

I'm often asked why we set a cross-sell goal of eight. The answer is, it rhymed with "great." Perhaps our new cheer should be: "Let's go again, for ten!"

Now, to be fair, my wife and I use more than a dozen financial products. But we don't live paycheck to paycheck, which, according to industry experts I've spoken to in the past, is the case for something like 40% of retail customers at the nation's biggest banks. Suffice it to say, if you're not saving money, you probably don't need a whole bunch of accounts.

And, in fact, this is exactly what happened at Wells Fargo. Take this exchange from last week's episode of NPR's Planet Money between podcast co-host Robert Smith and a former Wells Fargo employee named Ashley, who was fired after refusing to ply customers with accounts they didn't need:

SMITH: Ashley remembers one day when a man comes into the bank branch.

ASHLEY: He was elderly. He had a cane. He was on his own. The teller had sent him over to me the first day I met him because he was overdraft. And he couldn't understand why he was negative. And he was saying, all I want is to buy a newspaper. Why can't I buy my newspaper?

SMITH: Ashley pulls up his account on her computer. And she notices something really strange. This man was living off of Social Security. He got around $1,100 a month, and yet...

ASHLEY: Well, he had accrued, I think, over $200 in overdrafts. And when I looked at his accounts, he had six different accounts. He had no understanding of the accounts he had. He just said, oh, this nice lady explained to me that I needed this new account package like it wasn't an option for him. I felt so terrible for this man.

The point here is that it's very reasonable to think that this fraud started occurring long before even the earliest estimates that have surfaced over the past few weeks.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.