A Houston couple has pleaded guilty in an alleged plot to defraud the U.S. while working as contractors on rebuilding efforts in Afghanistan.

Seventy-three-year-old Delmar Dwayne Spier and his wife, 60-year-old Barbara Edens Spier, pleaded guilty Wednesday in U.S. District Court in Washington.

Their plea agreements require them to forfeit $3 million in proceeds from the fraud. Sentencing has not been set.

According to court documents, the Spiers were officers in Houston-based United States Protection and Investigations (USPI), a subcontractor for the U.S. Agency for International Development (USAID).

Dwayne Spier admitted defrauding the United States by obtaining reimbursement for inflated expenses on rental vehicles, fuel and security personnel. Barbara Spiers admitted to making up invoices from fictitious companies.