What is a 'baby replacement' abduction?

AUSTIN, Texas -- The case of a missing Austin mother and her infant daughter has captivated the entire country in a matter of days.

An autopsy confirmed the body found at a northwest Harris County home Thursday night is that of missing Austin mother Heidi Broussard.

READ MORE: Body of Austin mom found in trunk of car at Houston-area home:

According to records from the medical examiner's office, the body was found in the trunk of a car.

Broussard and her 3-week-old daughter hadn't been seen since Thursday, Dec. 12.

Baby abductions similar to this one have occurred in the past, and experts are breaking down the reasons why.

Beth Alberts, CEO of the Texas Center for the Missing and director of the Houston Regional Amber Plan, said there are very distinct elements of the Broussard case compared to past infant abduction cases nationally. She added that in these cases, the mother is always the one in danger.

Alberts said statistics and past cases show most abductions involving an adult and an infant done by a stranger are incredibly rare. In fact, it's less than one percent.

She said history also shows it's almost unheard of that a mother would run away or willingly leave her home with only one child when she has other children.

In Broussard's case, she and her 3-week old daughter, Margot Carey, were missing, but surveillance video captured her dropping her 6-year-old son, Silas, off at school before vanishing.

From what is known so far about Broussard's case, Alberts said it follows what is known to law enforcement as an "infant abduction" or "baby replacement." She said they're the only types of abductions that are typically done by women.

"When a very young infant is abducted, we often think that possibly it is a scenario called 'infant abduction' or 'baby replacement,'" explained Alberts. "Sometimes, when a newborn child is taken, these are the only abductions that really are done largely at the hands of a woman or perpetrated by a woman. Abductions tend to be male driven crimes."

A friend of Heidi, Magen Fieramusca, has been charged with kidnapping and tampering with evidence, namely a corpse in Broussard's case.

SEE ALSO: Woman charged in connection with kidnapping of Austin mom and baby

"Sometimes, a female loses an infant to a miscarriage or death or something and tries to replace the infant with another, very young infant that she can pass off as her own," said Alberts. "That is an unfortunate scenario, and it is a time when the mother is most at risk."

She also said those type of cases are extremely rare.

"It used to be more common when people could kind of go in a hospital and take a child and walk away," said Alberts. "But hospitals started putting in security measures to make that impossible now. So fortunately, it's rare, but does still happen."

Alberts said baby replacement cases almost always involve someone the mother knows, someone who has stalked the mother or someone who possibly was present throughout the pregnancy.

"It's not usually random. It certainly could be, but no, usually the person has sort of stalked the mother, watched the pregnancy and sometimes befriended the woman to get close to her and basically get access," Alberts said.

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