In the summer of 2007, a team of corporate investigators sifted through mounds of paper pulled from shred bins at Countrywide Financial Corp. mortgage shops in and around Boston. By intercepting the documents before they were sliced by the shredder, the investigators were able to uncover what they believed was evidence that branch employees had used scissors, tape and Wite-Out to create fake bank statements, inflated property appraisals and other phony paperwork. Inside the heaps of paper, for example, they found mock-ups that indicated to investigators that workers had, as a matter of routine, literally cut and pasted the address for one home onto an appraisal for a completely different piece of property. Eileen Foster, the company’s new fraud investigations chief, had seen a lot of slippery behavior in her two-plus decades in the banking business. But she’d never seen anything like this.