The state Department of Public Health has launched an investigation into the apparent medical overdose death last year of a patient at Kaiser Hospital in Oakland, NBC Bay Area’s Investigative Unit has learned.

Records show that over a 10-hour period in March of last year, the hospital doctors and nurses administered a combination of morphine-based painkillers, sedatives and a sleeping aid to the 41-year-old patient Teresa Panepinto.

The following morning, after a doctor twice failed to rouse Panepinto, a hospital nurse found her unresponsive. She never regained consciousness.

“She was a person with a great deal of love,” said William Panepinto about his daughter, a lawyer described by friends and family as a tireless advocate for homeless veterans. “It hurts to not have her with us. It hurts.”

Through medical records and interviews, NBC Bay Area’s Investigative Unit outlined what led to her death.

Although Panepinto had long suffered debilitating pain in her arms and hands that left her unable to work, her father, a longtime social worker who specialized in addiction, says she steadfastly resisted taking any opioid pain medication.

But she relented the week before her death because of new, unexplained pelvic pain, which eventually landed her at Kaiser Hospital at 4:30 p.m. on March 29 of last year.

Records show that over the course of 10 hours, Panepinto was given five doses of morphine-based drugs, along with two different sedatives and the sleeping aid Ambien. The fifth and final dose of morphine-based painkiller came around 2 a.m. March 30.

That was about the time Panepinto posted a photo on Facebook of her feet covered by a blanket on her hospital bed. She also phoned her parents in New York and left a message on their answering machine.

“This is Teresa, I’m sorry I’m calling so late, I just wanted you to know they have decided to admit me, so I will be staying in the hospital overnight,” Panepinto said to her parents. “OK, I’ll talk to you tomorrow. Love you. Bye.”

Five hours later, just after 7 a.m., medical records show a Kaiser doctor checked her pulse and breathing but was unable to wake her. Two hours later, at about 9 a.m., the doctor returned and told a nurse that Panepinto again could not be roused. Fifteen minutes later, that nurse found Panepinto blue and unresponsive.

Her parents immediately rushed out from New York. By the time they arrived in Oakland, William Panepinto said friends and family had just three days to say goodbye.

The Alameda County Medical Examiner determined Panepinto died from brain injury caused by the hospital giving her a lethal mix of drugs. An abdominal mass, likely the source of Panepinto’s pelvic pain, did not contribute to her death, according to the coroner’s report.

“We stood around her, we brought her Superman comforter that she had kept from when she was a kid,” William Panepinto said. “We put it on her, we talked to her, we sang a little bit, and she died by ten or eleven o’clock that morning.”

NBC Bay Area’s investigation also found that Kaiser did not alert state public health officials about Panepinto’s death, an apparent violation of state reporting requirements. The California Department of Public Health now tells NBC Bay Area it is investigating the incident.

Kaiser declined to be interviewed for this story, citing privacy laws and ongoing arbitration, but sent a written statement expressing condolences to the family and saying Kaiser complies with all reporting requirements.

“We extend our sympathy for the family on the loss of their loved one,” wrote Jeff Collins, senior vice president and area manager for Kaiser Permanente East Bay.

“Out of respect for privacy laws, we cannot provide additional information. At Kaiser Permanente, providing high quality, safe care is our highest priority. As part of our rigorous quality program we follow up and investigate any unusual or unexpected occurrences in the course of care. We comply with all regulatory reporting requirements and evaluate cases using established standards to determine when it is appropriate to file a report.”

While a Kaiser doctor eventually checked Panepinto’s pulse and breathing, NBC Bay Area found nothing in her medical records that documented constant electronic monitoring of her vital signs after she was given opioids and sedatives. The apparent lack of continuous monitoring troubles her father.

“She had no monitoring mechanisms on her while she was an inpatient,” Panepinto said. “There was no nursing presence in her room, which there would have been if she had been in the ICU.”

Dr. Anna Lembke, chief of Addiction Medicine at Stanford University, says combining opioids and sedatives compounds the risk of an overdose.

She authored a book on the prescription drug epidemic, titled "Drug Dealer, MD: How Doctors Were Duped, Patients Got Hooked, and Why It's So Hard to Stop."

“When we combine that opioid with a sedative, we increase the risk of slowing down the heart rate, slowing down the breathing rate,” Lembke said. “Patients fall asleep, gradually stop their breathing, and over the course of many hours, don’t wake up again.”

To avoid that, she said hospitals need to constantly track vital signs and be ready to act at the first sign of an overdose.

“We need protocols in place to make sure that the patient has not received so many opioids and so many sedatives that the patient is potentially not going to wake up again,” Lembke said.

In March of this year, the Panepinto family filed an arbitration claim against Kaiser.

The family’s attorney, Jim Keenley, was Panepinto’s classmate in law school. He says the medical records portray Panepinto as angry and hostile while she was at the hospital and suspects Kaiser sought a quick way to control a difficult patient.

“This death was caused by relying on the easiest available solution to deal with a frantic, suffering patient,” Keenley said. “Which is to give them easily administered medication that will calm them down and make them less of a problem on the emergency room floor.”

William Panepinto, who now takes Teresa’s backpack with him every time he travels, said he wants Kaiser to change its policies for sedatives and opioids.

“I don’t want this to happen again to more people,” he said.