PAWNEE COUNTY, Oklahoma - Investigators arrested a Ralston man they believe is connected to medical waste dumped along the Arkansas River in Pawnee County.

Tulsa police arrested Garrett Gibson for stealing used medical supplies from Tulsa's St. John Medical Center.

The hospital hasn't said much, other than it's cooperating with law enforcement; but a security memo sent out a few days ago said it appeared an unauthorized man had a key to secured wall boxes that held medical waste.

The memo said the man, believed to be Gibson, showed up to the hospital every few days for a week and went room to room removing the containers.

Once he was done, investigators believe the waste ended up in the Arkansas River.

Fisherman casting their lines out in to the water and dogs roaming the banks are some of the typical sights along the Arkansas River near Cleveland.

On Tuesday, however, scenery consisted of crime tape, syringes, needles and vials of mostly empty medicine.

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

It was a view that was easily summed up by a 16-year-old Kaylee Leon as, “Disgusted, very disgusted.”

Pawnee County Sheriff Mike Waters said biohazard containers carrying the dirty materials were thrown off two bridges -- the Belford Bridge near Ralston and the Highway 99 Bridge near Cleveland.

With the help of a Tulsa County air boat, Pawnee County investigators and an environmental scientist with the Department of Environmental Quality searched about 20 miles of bank and shoreline for any dirty supplies that might have been missed.

“With the wind and Mother Nature, there could be one or two that possibly got away or that we have not seen,” Waters said.

In all, close to 15 biohazard containers have been recovered in the past several days, and the sheriff said he has a person of interest.

“It makes me sick, it really does, for somebody to come out and jeopardize the citizens,” Waters said.

While deputies were on the water, the sheriff was interviewing Gibson, a Ralston resident who was arrested on Tuesday for stealing medical waste from St. John.

3/17/2015 Related Story: Ralston Man Arrested In Theft Of Medical Waste From St. John Hospital

The sheriff said it's highly likely Gibson is connected to the contaminated items found scattered along the river.

A Tulsa police report says Gibson was found carrying a small trash can in the hospital with needles and vials with small amounts of controlled substances in them.

Gibson reportedly had used a vial of pain medication.

The report says Gibson claimed he was a hospital janitor, but St. John said he was not an employee.

“We are one step closer and still moving forward,” Waters said.

Investigators did not find any new biohazard boxes on Tuesday, and environmental clean-up crews picked up all the medical waste that was scattered beneath the Highway 99 Bridge; it's being held now as evidence.

Some items did wash down river, but investigators don't believe too much contaminated material was carried away.