LOS ANGELES -- The family of a 17-year-old leukemia patient blamed Cigna Corp. on Friday for her death, saying the health insurance giant's initial refusal to pay for a liver transplant contributed to her death.

"They took my daughter away from me," said Nataline Sarkisyan's father, Krikor, with tears in his eyes at a news conference at his attorney's office.

The Philadelphia-based insurer had initially refused to pay for the procedure, saying it was experimental. The company reversed the decision Thursday as about 150 nurses and community members rallied outside of its office in Glendale in suburban Los Angeles. Nataline died just hours later.

The insurer "maliciously killed" Nataline because it did not want to bear the expense of her transplant and aftercare, said family attorney Mark Geragos.

Geragos also said he would ask the district attorney's office to press murder or manslaughter charges against Cigna, an allegation that one legal expert described as difficult to prove and "a little bit of grandstanding."

A district attorney's office spokeswoman declined to comment.

Nataline was diagnosed with leukemia at 14 and received a bone marrow transplant from her brother Nov. 21. She later developed a complication that caused her liver to fail. She was in a vegetative state for some time, her mother Hilda said.

Nataline was taken off life support at the University of California, Los Angeles Medical Center on Thursday, her mother said. Nataline died within the hour.

In a Dec. 11 letter to Cigna, four doctors had appealed to the insurer to reconsider. They said patients in similar situations who undergo transplants have a six-month survival rate of about 65 percent.

One of Nataline's doctors, Robert Venick, declined to comment on her case. UCLA Medical Center staff refused to make her other doctors available for comment.

The case raised the question in medical circles of whether a liver transplant is a viable option for a leukemia patient because of the immune-system-suppressing medication such patients must take to prevent organ rejection. Such medication, while preserving the transplanted liver, could make the cancer worse.

Transplantation is not an option for leukemia patients because the immunosuppresant drugs "tend to increase the risk and growth of any tumors," said Dr. Stuart Knechtle, who heads the liver transplant program at the University of Wisconsin at Madison and was not commenting specifically on Nataline's case.

The procedure "would be futile," he said.

Geragos' attempt to get the district attorney to press murder and manslaughter charges against Cigna would be difficult to prove unless the defense can show that the company somehow intentionally caused Nataline's death, said Rebecca Lonergan, a law professor at the University of Southern California.

"My personal opinion is that this is a little bit of grandstanding," said Lonergan, a former Los Angeles County and federal prosecutor.