PAWNEE COUNTY, Oklahoma - Four more containers filled with biohazard material were found on the Arkansas River. A boater found the containers near the Ralston Bridge this weekend.

The Department of Environmental Quality has had people searching the river since used medical supplies were found scattered in the river last week.

3/16/2015 Related Story: Medical Biohazard Containers Found Trashed In Arkansas River Near Ralston

In all, they've found about 19 containers - some opened, others still sealed.

While Garrett Gibson has not been charged for dumping the medical waste in Pawnee County, he has been charged in Tulsa County for stealing the containers from Saint John Medical Center.

3/17/2015 Related Story: Man Arrested For Medical Waste Theft Person Of Interest In Arkansas River Dumping

Investigators believe he took them in hopes of finding pain medication inside.