The cause of death for Michelle Trachtenberg, the “Gossip Girl” and “Buffy the Vampire Slayer” star, will remain undetermined as her family declined an autopsy, Variety has confirmed.

Families can decline autopsies when there is so evidence of foul play or for religious reasons. According to the NYPD, 39-year-old Trachtenberg was found “unconscious and unresponsive” at her New York City apartment on Wednesday morning. The Ems then arrived and pronounced her deceased. Criminality was not suspected and, as such, her cause of death will remain unknown.

Trachtenberg began acting at a young age, getting her start in commercials at three years old before landing her first TV role on the Nickelodeon series “The Adventures of Pete & Pete” in the mid-’90s. At age 10, she scored her first major film role with 1996’s “Harriet the Spy,” in which she played the title character. In the early 2000s, she played Dawn Summers...