Child actor Sophie Nyweide was pregnant when she died unexpectedly last week, according to a death certificate obtained by PEOPLE. Nyweide, 24, died on Monday, April 14, according to the Vermont Department of Health. Her pregnancy was first reported by TMZ .

Vermont authorities are investigating the death of Sophie Nyweide, a former child actor best known for her role in the film "Mammoth," as a possible unintentional overdose, according to a statement released by the Bennington Police Department.