Ka Yang, 29, of Sacramento was arrested on Tuesday, accused of killing her 6-week-old daughter by putting her in the microwave and pressing "start." On March 17, Yang had told authorities that her child had died after suffering a seizure. However, an investigation led to more grim circumstances.

CBS reports:

[T]he Sacramento Coroner determined Mirabelle Thao-Lo died from burns, however it could not be determined how she got them. After a three-month investigation that included consulting with several medical professionals and forensic specialists, police said they concluded that Mirabelle died as a result of being burned in a microwave oven.

Yang had three other children, who were taken into protective custody. While neither Yang's mental condition nor a motive are known at this time, neighbors told reporters that she often kept to herself. "She never opened the door," Margarita Layva told the Sacramento Bee. "She never came out."

Yangn was booked at the Sacramento County Main Jail. She is being held without bail.