BOULDER, Colo. (AP) — The Boulder County Sheriff’s Department has identified the chemical that sickened at least three dogs in Gunbarrel as an ingredient commonly used in pesticides and rodent poisons.

Investigators said Friday that the chemical was brodifacoum (broh-DYE’-fah-koom).

It was placed in up to eight meatballs that were first found in mid-April in a park popular with dog owners in Gunbarrel, just north of Boulder.

Deputies are still investigating, but no arrests have been made.

A reward for information now stands at more than $4,600.

Copyright 2014 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.