On Sunday, Travis County Sheriff's Office deputies, along with Texas Search and Rescue, searched Hippie Hollow and surrounding areas for Foster, but there was no update on his whereabouts.
As officials searched, Foster's family held a prayer circle.
His sister told KVUE Foster is a singer and described his loving personality as infectious. She asked anyone with information in regard to Foster's whereabouts to call them or the Travis County Sheriff's Office.
"We should be doing what we can as a community to spread the word because he can be anywhere," said Foster's sister, Adeelah Muhyee." We have been here 11 days and he is possibly not here, but he is somewhere and we need people spreading the word."
Muhyee told KVUE Foster usually calls or texts her every other day.
Travis County officials said they have used deputies, K9 units, a helicopter, drones and divers to search for Foster. TCSO said Foster is 5 feet, 10 inches tall with a slender build and may be wearing a nose ring.
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