The link above referencing the phone and piece of clothing being found is the first time, unless someone can show otherwise, this information has been released to the public. Even though it was mentioned LE nor the family have confirmed this information publicly. So, take the information for what it's worth.
It does however, lead to a LOT of other questions though; ie who were her last calls or texts made to?, did the phone's gps provide any further details about her travels that day?, what article of clothing was found?, what was the condition of her car when it was found?, was a forensic search completed of her vehicle?, etc.
Sadly, there are so many unanswered questions.