Rosie O’Donnell has reacted to the death of her Harriet the Spy costar Michelle Trachtenberg, who died at the age of 39. 

“Heartbreaking,” O’Donnell, 62, said in a statement to Us Weekly. “I loved her very much. She struggled the last few years. I wish I could have helped.”

Us Weekly confirmed Trachtenberg’s death on Wednesday, February 26. Police sources told Us that Trachtenberg was found unconscious inside her Midtown West Side apartment in New York City. The incident is not believed to be suspicious. No cause of death has been reported.

O’Donnell and Trachtenberg starred as Ole Golly and Harriet, respectively, in the film adaptation of Louise Fitzhugh’s 1964 novel of the same name. The movie marked Trachtenberg’s film debut, which began filming on her 10th birthday.

“I probably bonded with Rosie [O’Donnell] the most,” Trachtenberg told Uproxx in 2016. “She was very caring, and so funny. When we had to be serious for a scene we would, but we always went back to giggling and playing games when that scene was done. She was a very giving actor, even off camera.”

She added, “Any scene with Rosie was so special for me. She was amazing to work with, and we genuinely had a great time together. She respected me as an actress and I learned a lot from her. The hardest scene was saying goodbye to Golly.”

Trachtenberg said she had “several rounds of auditions in front of everyone involved in the movie” before earning the coveted role.

“I wore the same thing every time, a striped Gap T-shirt and overalls, which I keep in storage to this day,” she remembered. 

“I had a very outgoing personality and my mom and I worked hard on rehearsing the scenes round the clock — my passion for the role won the producers’ hearts,” Trachtenberg added. “I loved everything about Harriet, particularly that she was a writer because I had been writing stories from the second I learned how to write.”

Trachtenberg went on to star in Buffy the Vampire Slayer and Gossip Girl, among other roles on TV and film.