Shadle was last seen at the Walmart on North Atherton Street in State College. Police don't know whether she left there on foot or in a vehicle and they're concerned for her well-being.
Shadle struggled with a history of substance abuse, something police said makes her more vulnerable to crime.
"She's not contacted her children or other family members or friends since the last date she was seen," Ferguson Township Police Chief Diane Conrad said. "That's very unusual."
Police said she hasn't used her credit or debit cards or insurance cards since, either.
New information, released Friday, may be the answer investigators are looking for.
"In particular, we would like to speak with the men who shared refreshments with her on Friday evening, May 2nd, at the Champs Sports Grill on North Atherton Street," Conrad said.
Four men, described to police as middle-aged and Hispanic, had drinks with Shadle about two weeks before she disappeared.
Police said Shadle met them that night and don't believe she knew them before.
"We have been getting tips here and there and we've been following them up," Conrad said. "This is the only one we really haven't been able to identify the person."
Police said one of the men spoke English and paid for the tab using an American Express card. The signature is illegible.
Police hope these men, or someone who may know them, will come forward.
"They're not suspects, it was sometime before the disappearance," Centre County District Attorney Stacy Parks Miller said. "They just want to speak with anyone that may have talked to her in the weeks before she disappeared to see if there is anything relevant about it."
Parks Miller said everyone is doing what they can to find Shadle and she's hoping you can help.
"Everybody is on high alert," she said. "They're treating this woman as if she's a member of their family and they're not going to stop until they find out what happened to her."
"Missing" posters are being hung in windows all across Centre County. They're printed in English and Spanish. Police ask any area businesses who don't already have a poster to print one and hang it.
Anyone with information, no matter how much or how little, should call Ferguson Township Police at 814-237-1172 or 1-800-479-0050.
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