HULL (AP) – The Humane Society of the United States is offering a reward of up to $2,500 for information leading to the arrest in the suffocation of 3,800 pigs at a hog operation near Hull in northwest Iowa.

The Humane Society announced the reward Thursday.

The Sioux County sheriff’s office says deputies were called to the hog operation on Nov. 13 by the owner, Todd Hasche.

Authorities say someone overnight had tampered with the control to the building’s airflow system, causing the pigs to suffocate. Sheriff Dan Altena says the main breakers were turned off, a stand-by generator was turned off and the alarm system was disabled.

The loss of the pigs is estimated at more than $200,000.