The Sonoma County Sheriff's Department is investigating the sexual assault of a 28-year-old woman in the area of Boyes Hot Springs on Thursday night.
The victim reported the sexual assault Saturday, according to the sheriff's department.
The Sonoma Valley woman was walking in the area of Calle Del Monte and Vallejo Avenue around 9 p.m. Thursday when she was forced into nearby brush and trees by a man with an 8-inch kitchen knife, the sheriff's department reported.
The suspect was wearing a mask similar to that of the character Mike Myers in the movie "Halloween," according to the sheriff's department.
The suspect is described as having a stocky build with a deep voice. He was wearing a dark hooded sweatshirt and blue denim jeans.
Anyone with information regarding the case is asked to call the sheriff's department at (707) 565-2650.