Mollie Tibbetts Case: Could Red Shirt Hold the Key to Finding Missing Iowa College Student?

The search for Tibbetts has extended to a hog farm in Brooklyn, Iowa, near where she was last seen jogging.

Police are probing a possible break in the case of missing Iowa college student Mollie Tibbetts

A red shirt found Thursday near a previously searched hog farm may belong to the missing 20-year-old. It's the first major potential clue discovered in the search for Tibbetts, who hasn't been seen since July 18 when she left her boyfriend's home to go for a run.

A person mowing the lawn in the area found the article of clothing, which resembles a shirt worn by employees of a day care center where Tibbetts worked, according to Fox News.

Investigators are now scouring ditches near the hog farm for any sign of Tibbetts. 

On Thursday, her mother made an impassioned plea for her daughter's safe return.  

"We believe that Mollie is still alive, and if someone has abducted her, we are pleading with you to please release her," Tibbetts' mother, Laura Calderwood, said.

Calderwood said she still feels her daughter’s presence.

"Sometimes I just feel her sitting on my shoulder," she said. "Mollie was an incredibly strong young woman, and I don't know that I have the strength in me but Mollie is lending me her strength every day, every night."

Police have not commented on the shirt.