Michelle Trachtenberg's death has been ruled "undetermined".
The "Buffy the Vampire Slayer" star was found dead on Wednesday in a New York apartment at the age of just 39, and while her passing was not being treated as suspicious, it is still unclear what happened to the actress.
"People" magazine reports the New York City Medical Examiner's Office announced Trachtenberg's family objected to an autopsy, meaning only an external exam of the "Gossip Girl" star's body was allowed, leading to her cause of death to be ruled "undetermined".
The actress was reported to have undergone a liver transplant recently, and over the last few years, her fans have expressed concern about her health on social media.
And in 2024, the TV star actually took to social media to explain her gaunt appearance.
In response to a question about her health, Trachtenberg replied: "@cathy_critz explain to me how I look sick. Did you lose a calendar and not realize I'm not 14? I'm 38. How sad for you to leave such a comment. (sic)"
The "Harriet the Spy" star subsequently shared a selfie and insisted that she was feeling "happy and healthy".
The actress captioned the image: "I've received several comments recently about my appearance. I have never had plastic surgery. I am happy and healthy. Check yourself, haters. (sic)"
The New York Police Department (NYPD) officers had found the star's body when responding to a 911 call at 1 Columbus Place in New York City.
The NYPD added: "Upon arrival, officers observed a 39-year-old female unconscious and unresponsive. EMS responded to the location and pronounced the victim deceased. Criminality is not suspected."
Trachtenberg first found fame as a child, starring in TV commercials and the Nickelodeon series "The Adventures of Pete and Pete".
In 2000, the actress joined the cast of "Buffy the Vampire Slayer" as Dawn Summers, and between 2008 and 2012, she played Georgina Sparks on the hit teen drama series "Gossip Girl".