Baker, 43, originally faced seven felony drug charges but agreed to plead guilty in U.S. District Court to conspiring to distribute a mixture that contained painkillers oxycodone and hydrocodone and the anti-anxiety drug alprazolam, The Charlotte Observer reported.
In return, prosecutors dropped the other six charges.
The conspiracy charge is punishable by up to 20 years in prison.
Baker was sentenced to 15 to 18 years in prison after she pleaded guilty to second-degree murder in her 10-year-old stepdaughter Zahra's death. She also pleaded guilty to obstruction of justice, bigamy, four counts of obtaining property through false pretenses and two counts of identity theft.
Baker's husband, Adam, was charged with identity theft and obtaining property by false pretense for obtaining electricity from Duke Energy. Prosecutors said he used a family member's name to get electricity to his Hickory, N.C., home in August 2010.
On Thursday, Adam Baker pleaded guilty to a misdemeanor charge for stealing energy, WSOC-TV, Charlotte, reported.
He was ordered to pay $349 after pleading guilty to the charge.