Attorneys for a former Air Force nurse charged with killing three elderly patients by giving them lethal doses of medication say it would be negligent to undertreat pain for the terminally sick in their final days.

Capt. Michael Fontana faces three counts of murder when his military court martial begins Monday at Lackland Air Force Base. He faces life in prison if convicted.

Fontana is accused of knowingly giving deadly amounts of painkillers to three civilian patients placed on do-not-resuscitate orders last year at Wilford Hall Medical Center, the Air Force's largest hospital.

His attorneys say Fontana was a competent and caring nurse who comforted the ailing.

"It is recognized in end of life care that death is expected with this patient population and may coincide with medication administration simply due to the type and amount of medication that may be required to alleviate pain and anxiety for a particular patient," attorney Elizabeth Higginbotham wrote in an e-mail to The Associated Press.

She said Fontana will plead not guilty.

Higginbotham, one of Fontana's civilian attorneys, said her client "functioned in accordance with his duty to utilize professional nursing judgment" while treating end-of-life patients.

Last spring at an Article 32 hearing — the military equivalent to a civilian grand jury — Fontana's co-workers and medical experts indicated it was unlikely anyone with medical training would not understand the fatal risks of dispensing such high doses.

One of the alleged victims, a 74-year-old stroke patient, died after receiving 70 milligrams of morphine in a span of 70 minutes, a quantity doctors testified as very dangerous.

Another alleged victim was given a one-time push of 50 milligrams of morphine. Michael Shiels, a nurse who worked with Fontana at Wilford Hall, testified in May that he didn't "think the patient would even be breathing" before he could finish administering that amount.

Some of Fontana's former colleagues who testified against him in May described him as caring and well-liked by the families of his patients. Others testified they heard him discuss his "aggressive" reputation with treating end-of-life patients.

Military prosecutors have not yet offered a motive in court. The presiding judge over the Article 32 hearing recommended that prosecutors move forward with only one murder charge, but the military is going ahead with all three. Higginbotham said the judge's recommendation was based on the evidence offered.

Fontana, who also faces one count of conduct unbecoming an officer for altering medical records, has been in the Air Force since 2006 and served a tour in Iraq in 2007.

He worked as an intensive care nurse at Wilford Hall, which primarily serves military personnel and retirees but provides emergency and trauma care to some civilians.