The "Come & Get It" singer took to Twitter to remember her beloved friend, whose sudden passing on Saturday has left Hollywood in a state of shock.
The two had costarred in 2011's Monte Carlo, and on Sunday, Gomez posted an affectionate tweet about Monteith as she shared her grief.
"This hurts. I love you Cory. Rest in peace. My thoughts and prayers are with you and your family," she wrote.
Gomez then attached a photo of them hugging on the red carpet in 2011 at the Kids' Choice Awards.
Since news broke of Monteith's death, friends and fans have flooded Twitter with loving tributes to the Glee star. A rep for Monteith's girlfriend, Lea Michele, issued a statement requesting the public to "kindly respect Lea's privacy during this devastating time."
On Sunday afternoon, costar Matthew Morrison, who took the stage at Manhattan's 54 Below, dedicated his show to Monteith.
"You guys came to see a show, I came to perform a show, so that's what we'll do," he reportedly said. "And we'll do it in Cory's honor."
Monteith was found dead at the Fairmont Pacific Hotel in Vancouver after he missed his checkout time. Authorities have not disclosed additional details surrounding his passing, other than to confirm that there was no indication of foul play.
He had been at the hotel since July 6, and a video reportedly showed Monteith returning to his hotel room alone in the early morning hours.
A police source tells E! News that Monteith's case has been put on the fast track, and that autopsy results are expected to be released early this week.
"Due to the intense public interest, the toxicology will be expedited," notes the source, adding that results should arrive "in 2 or 3 days."
A spokesman for the Vancouver Police Department was unable to publicly confirm exactly when autopsy results would be released, but did confirm that the star's body is currently at the city morgue.
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