It was a scene riddled with inconsistencies.
First, the baby's mother claimed she had just suffered a seizure, yet paramedics observed no confusion, as expected in someone recovering from such an episode.
Her 7-week-old daughter, dead when authorities arrived, had suffered severe burns head-to-toe.
But detectives found no obvious sources for the burns in the Robla home.
And the infant's pajamas were mysteriously intact, her hair unsinged.
Then, inside the kitchen microwave, they found a pacifier.
Three months later, Sacramento police are alleging the unfathomable: that 29-year-old Ka Yang microwaved her baby to death.
On Tuesday, police arrested Yang on suspicion of murder and assault resulting in the death of a child under the age of 8. She also faces a special circumstance that the murder was intentional and involved the infliction of torture, which, if found true, would make her eligible for the death penalty or life in prison without the possibility of parole.
In requesting an arrest warrant, Detective Thomas Shrum laid out how police arrived at their gruesome conclusion about Mirabelle Thao-Lo's March 17 death.
Officers arrived at the Rood Avenue home at the request of firefighters, who were concerned about the infant's mysterious death.
Yang told family members, firefighters and, later, detectives that she had been holding the baby while working on a computer when she blacked out, the affidavit states. She woke up on the floor, next to a space heater, and the baby was injured, she said.
At one point, she told detectives that Mirabelle's hand was touching the heater, and that "a heater can heat up your whole body, including your insides," according to Shrum's warrant request.
But two firefighters on the scene before police noted that Yang appeared "alert and oriented" despite her claims she had just had a seizure, according to Shrum's warrant affidavit.
And after police pointed out discrepancies in her accounts, Shrum wrote, Yang admitted to lying to detectives and suggested she might have a split personality.
According to the affidavit, police reviewed Yang's medical records and found she had a history of seizures, for which she had been prescribed medication.
But detectives appeared to lay the groundwork for contradicting any defense that Yang could have put her baby in the microwave during or after a seizure, as was claimed in one of only three other known cases of children being injured or killed in a microwave.
They talked to former co-workers who had observed her physically violent, minutes-long seizures and said she was so dazed afterward that she had to be sent home. Those co-workers, and Yang's family, told police they had never seen her complete any "significant task" after a seizure, according to the affidavit.
Detectives also called upon the expertise of Dr. Lin Zhang, an associate professor of neurology at the UC Davis School of Medicine.
In an interview with The Bee, Zhang said it would be "difficult or impossible" for a person who suffered "tonic-clonic" type seizures, as Yang apparently did, to use a microwave during or after an episode.
"It would be a huge stretch," he said.
Detectives also interviewed pathologists involved in two of the known microwave burn cases.
One of them, Dr. Marcella Fierro, the retired chief medical examiner for Virginia, reviewed photographs of Mirabelle's body and said her injuries were consistent with microwave burns, according to the affidavit.
The Sacramento County Coroner's Office reached the same conclusion.
Unfortunately, heart-wrenching questions remain.
"Nothing (Yang) gave us explained what led up to the baby being killed," said police spokesman Sgt. Norm Leong. "We're asking the same questions that the community is asking, which is why and how could a mother do that? And what led up to it?
"Those are answers we don't have."