Police say the woman who killed a Houston mother and took her 6-week-old baby earlier this week was trying to cover up a miscarriage.

The murder and kidnapping led to a nationwide Amber Alert for 6-week-old Shamali Flores, who has since been found safe, according to the Houston Police Department.

Related: 6-week-old found safe at southwest Houston apartment

Police announced Thursday morning Erica Miranda-Alvarez, 28, is charged with capital murder for the death of the little girl's mother. According to investigators, Miranda-Alvarez knew the victim through the victim's brother. She allegedly killed the mom and took the baby in an attempt to cover up her own miscarriage, said HPD Chief Art Acevedo.

Police along with SWAT officers and FBI arrested Miranda-Alvarez outside an apartment complex building on S. Gessner around 1 a.m. Thursday. The woman was with her boyfriend when she was arrested. Police say he remains under investigation but is not charged with any crimes.

Miranda-Alvarez was scheduled to appear in court Thursday evening. Her charges were read during her scheduled court appearance, but she was not present, as she was being held in a medical unit. The charging document alleges Miranda-Alvarez used scissors in the murder.

The 6-week-old girl was taken to Texas Children's Hospital where she was found to be healthy.

Watch: New details released by HPD at press conference

Shamali's mother, identified as Carolina Flores, was found fatally stabbed Tuesday afternoon at an apartment complex on Goodson Road in the Greenspoint area of northeast Houston.

Related: Mom murdered, baby missing from Greenspoint apartment

An AMBER Alert has been issued for a baby girl police say went missing after her mother, identified as Carolina Flores, was found stabbed to dead Tuesday afternoon in the Greenspoint area.

On Wednesday, the FBI and Equusearch joined police in the search for the missing child. The girl's father, who was initially believed to be a suspect, was later cleared after he was questioned in San Antonio.

Investigators say a detective went to the Woodscape Apartments at 9707 S. Gessner early Thursday and was joined by several officers, FBI agents and SWAT officers. Police saw the female suspect and her boyfriend with the baby, who matched the description of the child in the Amber Alert.

They say it appeared the couple was trying to leave with the baby, but they were taken into custody without incident. Chief Acevedo say the suspect gave up quickly and did not put up a fight.

The little girl is now in the care of Texas Child Protective Services.

Acevedo says investigators are now working to piece together every aspect of the crime to not only get an arrest and a charge "but also a conviction."

Investigators have already determined the suspect suffered a miscarriage in January. She allegedly told family members her newborn was sick in the hospital soon after the child was supposed to be born. She then kidnapped 6-week-old Shamali Flores in an attempt to claim her as her own.

Police say the suspect, Miranda-Alvarez, came to the United States five years ago and befriended the victim's brother.