Trachtenberg was found dead in New York City on the morning of Wednesday, Feb. 26

Michelle Trachtenberg in 2020. Photo:JC Olivera/WireImage

Michelle Trachtenberg was reportedly “struggling” before her sudden death.

The Gossip Girl alum was 39 years old when she was found dead in New York City on Wednesday, Feb. 26. A source tells PEOPLE that in the year prior, Trachtenberg was “really down emotionally.” She also had been dealing with “health issues.”

“She told friends she was struggling,” the source says. “She was really, really sick and open with those in her circle about how much she was struggling.”

Physically, the insider claims Trachtenberg looked “pale, gaunt” and “very thin.”

Michelle Trachtenberg in 2021. Chandler Allen/BFA.com/Shutterstock 

Around 8 a.m. on Feb. 26, police responded to a 911 call at 1 Columbus Place in New York City, the NYPD confirmed to PEOPLE. “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.” 

The investigation is still ongoing. The New York Post was first to report.

PEOPLE learned Trachtenberg had recently undergone a liver transplant. A source told ABC News that may have led to complications.

Never miss a story — sign up for PEOPLE’s free daily newsletter to stay up-to-date on the best of what PEOPLE has to offer​​, from celebrity news to compelling human interest stories.

Although Trachtenberg did not publicly reveal any health conditions, she did respond to people questioning her wellbeing after she posted a selfie to her Instagram in January 2024.

“Fun fact. This is my face,” she captioned a follow-up post. “Not malnutrition no problems. Why do you have to hate? Get a calendar.”

She then shared another post, writing: “I’ve received several comments recently about my appearance. I have never had plastic surgery I am happy and healthy. Check yourself haters.”

Trachtenberg got her start in commercials before landing roles on Nickelodeon’s The Adventures of Pete & Pete and All My Children at 9 years old in 1993. She went on to star in Harriet the Spy in 1996, and then took on the role of Dawn Summers, Buffy’s little sister, in Buffy the Vampire Slayer.

From 2008 through 2012, Trachtenberg played Georgina Sparks, a recurring character on the hit series Gossip Girl. In 2023, she reprised the role for two episodes of the Max reboot, which ultimately marked her last onscreen appearance.