Taking that as a sign, Dore immediately sealed the empty office Brown and Livingstone shared and began searching its contents. The search uncovered bags of expensive dental tools and prostheses, which it turned out he had been illegally selling to dental students for years. Knowing vendor kickbacks are common$$and since one of the main functions of the business office was to process invoices submitted by vendors$$Dore started by reviewing the master file. The list had never been purged and contained tens of thousands of names$$all the vendors who had ever supplied goods and services as part of the college$$s annual budget of $$55$ million. He selected $50$ vendors, deliberately choosing those without a phone number or street address. Then Dore took his list to the next stop in the payment process, the accounts payable department. After methodically pulling all corresponding documentation, he quickly focused on one vendor: Armstrong Supply Company. It regularly billed two or three times a month for strange items named but unknown by Dore and always for amounts under $$4,500,$ thus eliminating the necessity of two authorized signatures. All of the request$-$for$-$funds forms attached to the invoices either bore the signature of Livingstone or the dean of the dental school. Furthermore, Dore could find no vendor application on file for Armstrong Supply. He also failed to find any competitive bidding process in place. $$Once I looked at the actual invoices, that really got me going,$$ said the fraud examiner. Some carried invoice numbers; others did not, but they did carry a four$-$digit post office box number. $($Subsequent research revealed that postal authorities had switched to five$-$digit and six$-$digit PO boxes years earlier.$)$ Billed items included such things as $3$ dozen TPM pins$($the identity of which baffled even the long$-$time stockroom manager$).$The invoices just smelled fake,$$ said Dore, who packs more than $20$ years of auditing experience. What$$s more, he later found blank invoices for Armstrong Supply in one of Brown$$s desk drawers. He even noticed one completed invoice that had been readied for submission. $($Apparently$,$ Brown left in too much of a hurry to dispose of the smoking gun.$)$ Based on those questionable invoices, the accounts payable department would issue a check for the stated amount. On the request$-$for$-$funds forms attached, Brown always indicated that she would personally present the check to Armstrong Supply. $($Due to lax controls, vendors and employees were allowed to pick up checks.$)$ Canceled checks revealed that a man named Claude Armstrong III cashed them at various check$-$cashing services, which sometimes called Cheryl Brown for additional verification, as noted on the backs of the checks. Further research showed yet another scam, according to Dore. The office mail contained a department store gift card with a note from a vendor to Brown, thanking her for her recent business. The California vendor had billed the college for roughly $$42,000$ worth of copy machine cartridges$$running $$4,500$ apiece$$and Brown had processed the invoices. After a fruitless search for this valuable cache in the school$$s storerooms and copy centers, Dore called local dealers and discovered that their most expensive cartridge cost only $$483.$ Under his direction, private investigators located the vendor$$s $$corporate headquarters$$ in a rental unit at a retail postal center, but the college abandoned their long$-$distance pursuit of recovery when it proved too costly$.$ Although Dore tried to keep his three$-$month$-$long investigation quiet, the campus buzzed with news of his activities. Brown$$s many friends, including two in the accounts payable department, kept her abreast of his movements. Next he pulled in Livingstone for a chat about the new evidence supporting vendor fraud and kickbacks, as well as his backroom sale of orthodontic supplies. According to Dore, it became apparent during the interview that the philanderer knew nothing about the vendor schemes. Brown had perpetrated the $$63,000$ vendor fraud without Livingstone$$s help. He seemed quite taken aback that it had occurred under his nose by someone he trusted so much. In some cases, Brown had forged the signatures of her supervisor and the dean of the dental school. In others, the unwitting bosses actually signed the bogus forms.

What kind of scheme was Brown running? Describe the scheme.