When Did Kate and Sara Know Maura Was Missing?

Maura had made two good friends at UMass: Kate Markopoulos and Sara Alfieri. I'd like to know when they knew Maura was missing.

According to Fred, he didn't know Maura was missing until early evening, Tuesday. Unless Maura spoke to Kate and Sara about her plans, whatever they were, two days have gone by with Maura flying under the radar. Why didn't Kate or Sara start looking for her before Fred? They would have known that Maura had disappeared by then. She wouldn't have been answering her phone or door. Wouldn't her two closest friends wonder where the hell she was?

I can't ever get a straight answer out of Kate. And the only time I have managed to speak to Sara, her only question was "How the hell did you find me?"

Early on, Helena Dwyer, the woman who runs the Facebook group, explained that Sara gave Fred important details about Maura but would not ever tell them to a reporter. I wonder if Sara ever gave those details to investigators.