Distraught Mom: 'My Son is Missing'

“I put him in his crib, and now he’s not there. And there was a knife laying next to my bed.”

This excerpt from a 911 call is Brianna Marshall,  an 18-year-old mother who realized  her newborn  baby had gone missing.

Marshall called police distraught to report newborn Kayden Powell had disappeared.

Also gone, Kristen Smith,  her half-sister who's now charged with the abduction.

The FBI says  Smith confessed to taking the newborn and leaving him in a plastic storage bin.

Investigators say they found online conversations where she claimed to be pregnant.