The baby monitor on Alexa's bedside table crackled softly as 8-month-old Mateo cooed himself back to sleep. She sat in the rocking chair near the baby's crib, gently smoothing down Mateo's soft brown hair. Her heart still aches with fresh grief over Micah's disappearance, but these days, her focus has to be on keeping Mateo safe. Her palm traced circles on his back as he drifted off.

Alexa's voice quivered as she sang softly.

“Hush, little boy… mama's right here.”

Behind her, the late ...