Kauai police are helping investigate the poisoning of five animals in a Kalaheo subdivision.
Officials say the four dogs and one cat were poisoned by a common pesticide used to kill unwanted plants.
State Department of Agriculture spokeswoman Janelle Saneishi says paraquat was used in the Jan. 25 poisonings.
The Garden Island reports the police department is working with the humane society to investigate.
Kauai Humane Society field services supervisor Mana Brown says it's not known if the restricted use pesticide was being thrown on a yard or if the animals got to it another way.
Agriculture officials have handed out flyers warning residents to not let pets roam freely.
Deliberate misuse of a pesticide carries punishment of up to a year imprisonment, a $25,000 fine or both.