In the late 1990s, payment records show, Ms. Green got her mortgage back on track for about five years. Then a previous loan servicer began misapplying some of her payments, Mr. Rothbloom said. In January 2004, he took her case, filing a bankruptcy proceeding to stave off a foreclosure.

Wells Fargo took over servicing Ms. Green’s loan in May 2004. Mr. Rothbloom kept trying to determine who owned the loan and how much Ms. Green owed so that they could complete her case. “We filed a Chapter 13 bankruptcy to cure the arrearage, and we could never get a clear answer or supported answer as to what that arrearage was,” he said. “Bankruptcy rules require supporting documentation.”

Since then, he said, Ms. Green, 71, has paid her loan on schedule to a unit of Wells Fargo.

After two years passed, Mr. Rothbloom still had not received a complete and accurate accounting of Ms. Green’s loan. So he filed suit in May 2006 to determine who owned the note on her property. Because three institutions claimed ownership but none could produce the original note, Mr. Rothbloom began conducting discovery. During this exercise, three different Wells Fargo employees made three different representations to the court about the whereabouts of the note.

Story No. 1: The note was lost. Wells Fargo’s lawyers produced a sworn statement to that effect made on Oct. 20, 2004, by Lisa Joseph, a Wells Fargo employee. But that affidavit was incomplete. The section where Ms. Joseph was supposed to describe the diligent search she had conducted to find the note was blank. The document also said that a copy of the mortgage was attached. It wasn’t.

Hoping to verify that no one else might be holding the supposedly lost note, Mr. Rothbloom asked for Ms. Joseph’s deposition. Wells Fargo’s lawyers refused to supply her address. Instead, the bank produced an employee who knew nothing about the loss of the note or what Ms. Joseph had done to try to find it.

It was during that interview, in July 2006, that Story No. 2 emerged. The Wells employee said that the note had never been transferred to the bank, ergo, Wells could not have lost it, as Ms. Joseph had previously sworn.

Two months later, Wells filed a brief conceding that it did not own a security interest in Ms. Green’s loan but asking the court to dismiss Ms. Green’s suit. The court refused.