Mitchelle Blair, 35, was also arraigned on two counts each of felony murder, premeditated murder and torture.
Court officers conducting a March 24 eviction at Blair's eastside apartment discovered the frozen corpses of 13-year-old Stoni Ann Blair and 9-year-old Stephen Gage Berry beneath plastic in the freezer.
State officials will conduct forensic tests to establish whether Blair is competent to stand trial. Her attorney also requested an independent psychiatric evaluation to discover if she is competent to stand trial and if she was competent to waive her Miranda rights before investigators say she confessed.
Defense attorney Wyatt Harris told reporters that Blair struggles to discuss the case with him.
More From This Section
"There are times when she can communicate in a very effective manner. Then, there are times when she can't," Harris said outside the courtroom.
Autopsies determined both of Blair's dead children had been beaten. Investigators believe Stephen died in August 2012 and Stoni died the following May.
Blair's surviving children, a 17-year-old girl and 8-year-old boy, have been placed in a relative's care. The state Department of Human Services filed last week to end Blair's parental rights.
"Blair tortured Stephen for approximately two weeks prior to his death by tying a belt around his neck, throwing hot water on him while in the shower and putting a plastic bag over his head," the state said, quoting the 17-year-old.
Stephen was "unresponsive" on Aug. 30, 2012, and Blair wrapped his body in bed linen and put him in the freezer, the state said.
King entered a not guilty plea on Blair's behalf and scheduled her preliminary examination for June 19. She was ordered to remain jailed.