FARGO, N.D. (AP) - An appeals court has thrown out a guilty plea of a North Dakota woman accused of disguising tainted drug money in order to get her son out of jail.

Tamara Heid was convicted in federal court of conspiracy to launder money and sentenced to 18 months in prison. A judge had denied her request to withdraw her guilty plea before sentencing.

A three-judge panel of the 8th U.S. Circuit Court of Appeals said in a ruling released Thursday that there's no evidence Heid conspired to conceal or hide the source of the money.

The case has been sent back to district court.

Heid's son, Donavan Slagg, is serving a mandatory life prison sentence on a drug conspiracy conviction.