The girl was being housed in a downtown hotel April 1 when she was seriously assaulted and left for dead.
Police initially said she was located by officers 11 minutes before she was reported missing.
But Constable Eric Hofley, a police spokesperson, says police have since learned that there was also an earlier call made by another child welfare worker who reported the girl missing.
Hofley would not say when that call was made — only that it was before police found the girl.
Police have charged a 15-year-old boy — who was also in care and being housed at the same hotel — with aggravated assault and aggravated sexual assault.
Police say the two were known to each other.
The case has renewed questions about Manitoba's child welfare system and the quality of care being given to kids housed in hotels.
The Manitoba government promised to end the use of hotel rooms for child welfare in 2006, but has said the practice has continued due to a shortage of alternatives such as foster homes.
Family Services Minister Irvin-Ross renewed the promise last year, when 15-year-old Tina Fontaine was killed after running away from a hotel.
Thelma Favel, Fontaine's great-aunt, has said Tina was a frequent runaway and social workers simply dropped her off outside the hotel instead of taking her inside.
Tina left the hotel and her body was found days later, wrapped in a bag in the Red River.