Abigail Breslin Mourns 'My Sister's Keeper' Costar Evan Ellingson, Former Child Star Dead at 35

Following the news of his death on Tuesday, the 27-year-old actress took to Instagram to mourn the death of Elliingson, who played her onscreen brother in the 2009 drama.

Alongside a photo of herself, Ellingson, and Sofia Vassilieva from My Sister's Keeper, Breslin wrote, "Evan Ellingson was a kind, funny and extremely talented human being. He played my big brother in a film I did called My Sisters Keeper. Evan was a genuinely thoughtful person who cared so much about turning in the best performance, which he accomplished."

"Some of his scenes in MSK still give me chills," she continued. "He was also silly, funny, a prankster, a lover of Red Bull (I hated the smell of Red Bull 😂) and he was energetic and the life of the party. I didn't keep in touch a lot with him after the film, but he always stayed in my mind as a wonderful and sweet soul, one I am grateful to have crossed paths with. My prayers and condolences are with his family at this difficult time."

Breslin added, "Evan, I know Heaven will welcome you with open arms. Your time on this earth may have been, devastatingly, short. Your humor, exuberance, kindness and bright light will linger forever. Sending you peace on your journey to the great beyond and who knows… maybe one day, I’ll meet you in Montana. Xx, abster."

After concluding her tribute, the Oscar nominee added a message for fans, writing, "Side note: the details of Evan’s passing have not yet been released. I ask you to kindly not speculate on the details out of respect for his family including his daughter."

Breslin also posted another photo of herself and Ellingson from My Sister's Keeper, with the two playing in the water. "RIP, bub," she wrote over the shot, adding a series of heart emojis.

According to TMZ, Ellingson passed away on Sunday. His father told the outlet that the late actor was discovered at a sober-living home. While Ellingson previously struggled with drugs, he was reportedly in a much better place recently.

The cause of Ellingson's death is currently unknown.

Ellingson was best known for his roles in My Sister's Keeper, in which he starred alongside Breslin and Cameron Diaz, and CSI: Miami, in which he had a guest starring role. According to his IMDb profile, his last on-screen appearance was in a 2010 episode of CSI: Miami.