An Arkansas couple admitted their role Tuesday in a black-market scheme to buy nearly $1.4 million worth of printer ink stolen from the City of Philadelphia.

In a hearing before U.S. District Judge Jan E. DuBois, Derek and Danita Willis, owners of the Russellville, Ark.-based Laser Cartridge Plus, pleaded guilty to five counts of mail fraud, obstruction of justice, and perjury. They will be sentenced later this year.

Federal prosecutors said the Willises obtained their illicit ink from a mail room clerk working within the Philadelphia Water Department. That man - Calvin Duncan, 63 - told a judge in August that he ordered the ink through the city's procurement process and later sold it for $545,000 to the Willises. He is scheduled for sentencing in July. - Jeremy Roebuck