Supermodel Cindy Crawford has said she and her family are "beyond heartbroken" over the death of her son Presley Gerber.
"He is a sweet, beautiful soul who loved and is loved, now and forever," she posted on Instagram, next to a black-and-white photo of him. "We are so proud of how he showed up in the world, with kindness and vulnerability."
The 27-year-old died on 20 September at a rehab facility in California. Police said officials are investigating his death as a suspected overdose.
Gerber had been a model like his mother and younger sister Kaia, making his catwalk debut for Italian label Moschino aged just 16.
Crawford wrote in the post on Sunday: "We feel so blessed to have had Presley in our lives for 27 years."
"We are grateful for the outpouring of love and support from so many who know and love our family and even strangers who feel our pain," she also posted.
"Til we meet again our sweet boy. We love you forever, Mom, Dad and Kaia," she wrote in closing, with an emoji of angel wings.
The tribute also listed the dates of his birth and death.
The Los Angeles County Medical Examiner lists Gerber's case as pending additional investigation. The Santa Monica Police Department has said there is no indication foul play was involved in his death.
Gerber's sister Kaia also dedicated a post to him on Sunday which included a video of the two siblings as children dancing together, a photo of them standing near the ocean, and a four-page letter to "prez" typed out on a blue background.
In the letter, she said she had been scared of getting her ears pierced, so "you went first".
"But when I held the earring they took from your body, all I could think was: That belongs to you," she wrote.
"I am learning how to love you when I cannot see you," she also wrote. "How to tell you something without picking up my phone to call you. How to be your sister in a world that I can't reach for you in," she wrote.
In recent years, Gerber had spoken openly about his mental health challenges and drug use and frequently posted videos on Instagram himself for what he called "Mental Health Mondays".
His father Rande Gerber, a well-known businessman, co-founded the Casamigos tequila brand with George Clooney.
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