Sarah Michelle Gellar Speaks Out Following ‘Buffy’ Co-Star Michelle Trachtenberg’s Death

Sarah Michelle Gellar is paying tribute to her late Buffy the Vampire Slayer co-star Michelle Trachtenberg following the actress’ death on Wednesday, Feb. 26 at the age of 39.

Gellar, 47, took to Instagram after news broke of her on-screen sister’s passing, sharing a photo of their characters, Buffy Summers and Dawn Summers, in the 2001 episode “The Gift.” “Michelle, listen to me,” Gellar captioned the post, repurposing a moment between the Summers sisters from the episode. “Listen. I love you. I will always love you. The hardest thing in this world, is to live in it. I will be brave. I will live … for you.”

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The Dexter: Original Sin actress also included pictures from throughout their friendship, one of which featured Shannen Doherty, who died at age 53 in July after a battle with breast cancer.

Trachtenberg was found “unconscious and unresponsive” in her apartment around 8 a.m. on Feb. 26, the New York Post was first to report. The Harriet the Spy star was pronounced dead at the scene and an investigation into her death remains ongoing, police said, but no foul play is suspected. Sources told the outlet that Trachtenberg had undergone a liver transplant within the last year, which may have led to complications with her death.

Following the news of Trachtenberg’s passing, several of her Buffy the Vampire Slayer co-stars took to social media to pay tribute. David Boreanaz, who played the vampire Angel, wrote on his Instagram Story, “So very sad …horrible news. RIP and prayers to her and her family.”

Alyson Hannigan, who played Buffy’s best friend Willow Rosenberg, also shared a memorial post on Instagram, writing, “I am deeply saddened by the news of Michelle’s passing. She brought a loving energy to the set of Buffy. My thoughts are with Michelle’s family and friends.”

James Marsters, who played the vampire Spike, expressed his grief in a statement to PEOPLE, saying, “My heart is heavy today. We have lost a beautiful soul.”

“Michelle was fiercely intelligent, howlingly funny and a very talented person. She died much too young, and leaves behind scores of people who knew and loved her,” he continued. “My heart goes out to her family, who are good people and are suffering the greatest loss anyone could bear. I hope everyone can give them space to heal in this most difficult time. Godspeed Michelle. You are missed.”