The 3-year-old girl vanished last Saturday morning after police said her father, Wesley Mathews, left her outside for not drinking her milk.
Police said he claimed she was placed near a tree in alleyway where coyotes were known to roam. When he returned for his daughter 15 minutes later, he said he could not find Sherin.
But now, investigators said they are hoping someone has surveillance video after learning someone left in the family's SUV the morning the girl disappeared.
Missing North Texas toddler left near coyote-infested alley as punishment, police allege
Police believe if such a video exists, it might shed light on Sherin's disappearance in Richardson.
The SUV returned to the home an hour later. Richardson police said her father called 911 sometime thereafter.
Investigators could not say who drove the SUV away from the home.
Wesley has been charged with child endangerment and is now out of jail wearing an ankle monitor.
Amber Alert issued for missing 3-year-old near Dallas