The death of former child actor Marion "Sophie" Nyweide is being investigated as a "possible unintentional overdose," police said this week.

Nyweide, 24, who appeared in movies such as 2014's "Noah" with Russell Crowe and 2009's "Mammoth" with Michelle Williams, was pronounced dead in the early hours of April 14 after police were called to a riverbank in Vermont to respond to a report of an unresponsive female, according to the Bennington Police Department.

Police called the investigation "fluid" in a news release Tuesday, noting that they were waiting on the results of a final autopsy and toxicology reports from the Vermont Office of Chief Medical Examiner.

In the release, police said they were dispatched to "a wooded area along the banks of the Roaring Branch River located off of Park Street in Bennington, Vermont," after receiving the initial report.

After police attempted "life saving measures," Nyweide was pronounced dead just before 5 a.m., according to the release.

"An individual was present with Nyweide at the time of her death and they are cooperating with investigators. The same individual was the person who contacted 911, summing [sic] assistance for Nyweide," police stated in the release.

According to police, the matter is being investigated "as a possible unintentional overdose."

The police said the investigation remains open.

Nyweide's credits include a number of film and TV roles, including an episode of "Law & Order" and "What Would You Do?"

ABC News has reached out to Shelly Gibson, Nyweide's mother, for additional comment.