Sonoma County Sheriff’s Office spokeswoman Sgt. Cecile Focha said Tuesday deputies recently identified a person of interest in the poisoning case, but authorities would not give any details.
The San Francisco Chronicle reports the animals became ill on Feb. 12 after someone planted the homemade cookies on the woman’s property in an unincorporated area of Sebastopol.
Necropsies on the horse and dog that died revealed they had ingested oleander, a plant that is poisonous to horses, dogs, cats, cows and birds.
Deputies said the case appears to be an isolated incident, and authorities have warned neighbors near where the poisoning occurred.