By Tony Hanson

PHILADELPHIA (CBS) — A former Philadelphia Water Department mailroom clerk has been indicted by a federal grand jury on charges that he cheated the city of nearly $1.4 million over a six-year period in a printer-ink and toner-cartridge scam.

Officials say the investigation of defendant Calvin Duncan started with a tip from another city employee.

Duncan, 61, had the job of purchasing printer ink and toner cartridges for the city water department, but the grand jury alleges that he purchased plenty of extras — which he sold under the table to a couple running a resale company in Arkansas.

“Derek and Danita Willis allegedly paid Duncan over a half million dollars — approximately $545,000 — which was not due to him, for the printer ink and toner cartridges,” explains assistant US attorney Tomika Stevens.  “And those cartridges were  purchased with City of Philadelphia funds and shipped to Laser Cartridge Plus, using the water department’s own UPS shipping account.”

The Willises are also charged in that alleged scheme.  They are also charged with obstructing justice by destroying documents and lying to the grand jury.

Duncan has been fired from his Philadelphia Water Department job and now faces a possible 100 years in prison and a $1.25-million fine if convicted on all charges.  He was expected to surrender later this week.  The Willises face similar penalties.