West Mercia Police have confirmed Georgia Williams' Twitter account has been checked as part of their investigation.
On Sunday evening, the 17-year-old wrote on the site that she had "stuff on [her] mind".
Superintendent Nav Malik said they were speaking to Georgia's family to try and understand its meaning.
"We are aware of that tweet, we're not sure of the significance of it, it would be nice to know.
"We're doing some work with [Georgia's] siblings to try and understand what may have been preoccupying her mind."
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After a chilly start, Thursday looks set to be a fine, crisp autumn day with light breezes and good spells of sunshine across the region.
A dry and often sunny day is expected with light and variable winds. Feeling cooler with temperatures slightly lower than Wednesday.
A clear night. Dry and sunny weather to end the week.