Updated

Nearly four years after a concerned official wrote an anonymous letter about an East Texas dialysis clinic's alarming number of emergency calls, a nurse is on trial Monday on charges she killed five patients by injecting their dialysis tubes with bleach.

Kimberly Saenz, 38, is charged with capital murder in the deaths and aggravated assault in the case of five other patients injured at the DaVita Dialysis clinic in Lufkin. She has pleaded not guilty and has been free on bail. Prosecutors say they'll seek the death penalty if she's convicted.
Saenz was charged a year after a top Lufkin fire official wrote an anonymous letter pleading for state health department inspectors to take a look at the clinic because of numerous calls for paramedics.

"In the last two weeks, we have transported 16 patients," the April 2008 letter said. "This seems a little abnormal and disturbing to my med crews. Could these calls be investigated by you?"

State medical surveyors arrived at the clinic about 125 miles northeast of Houston within days. Emergency crews had by then been called as many as 30 times that month, including seven for cardiac problems, and made at least 19 runs. Four people had died.

There had been only two calls during the previous 15 months, according to the Texas Department of Health Services.

Inspectors were present on April 28, 2008, when two dialysis patients said they suddenly didn't feel well and two others reported that they saw Saenz inject bleach into tubing used by fellow patients Marva Rhone and Carolyn Risinger.

Saenz, who had held her entry-level position as a licensed vocational nurse for eight months, was sent home. Police were summoned and the clinic was temporarily shut amid fears patients were in immediate jeopardy. Saenz was fired the next day.

A year later, an indictment listed sodium hypochlorite, commonly known as bleach, as a "deadly weapon" used by Saenz to kill five people, including Rhone and Risinger. The disinfectant is a normal cleaning solution used at medical facilities.

All parties in the case are under a gag order from State District Judge Barry Bryan that blocks them from speaking about it outside the courtroom. But Saenz's lawyers previously have said she had no motive to kill.

"Kimberly Saenz is a good nurse, a compassionate, a caring individual who assisted her patients and was well liked," defense attorney T. Ryan Deaton said in a recent court motion.

Saenz also swore in an affidavit she had no previous felony record.

But documents filed by Angelina County District Attorney Clyde Herrington listed about a dozen instances of wrongdoing he planned to present to jurors, including allegations Saenz overused prescription drugs, had substance abuse and addiction problems, was fired at least four times from health care jobs, put false information on an employment application and sought a health care job in violation of terms of her bail.

Federal investigators examined blood tubing, IV bags and syringes used by the DaVita patients, who spent up to three days a week tethered for hours to a machine that filtered their blood -- a job their kidneys could no longer do.

A Food and Drug Administration report found some samples linked to some victims tested positive for bleach while others showed bleach "may have been present at one time."

Clinic policy calls for bleach to be used in various concentrations to clean blood from surfaces, chairs used by patients and internal machinery parts. Chemical reactive agents then are used to confirm bleach residue was removed and the cleaned areas are safe.

Deaton has insisted his client has been a scapegoat for clinic mistakes and policy violations. State health department investigators found dozens of "adverse occurrences" such as incomplete and undated entries on logs required to document disinfecting procedures.

He also has questioned whether bleach caused the patients' ailments.

"Chest pain and cardiac arrest are not specific for bleach infusion," he wrote in one motion.

A review of clinic records by an inspector affiliated with the federal Centers for Disease Control and Prevention found Saenz was on duty for 84 percent of the instances where patients suffered chest pain or cardiac arrest. Deaton said one other clinic staffer was there for all the instances and another for 89 percent.

Joel Sprott, an attorney for clinic operator DaVita Inc., said the Denver-based company has turned over more than 10,000 pages of records in the case. Through 2011, DaVita operated or provided services to 1,809 dialysis facilities in the U.S., serving some 142,000 patients and employing more than 41,000 people.

Citing the gag order, DaVita spokesman Vince Hancock would only say last week only that the company looks forward "to continuing our steadfast commitment to the Lufkin community."