A former beautician who injected cooking oil into a woman's buttocks as an anti-aging treatment, killing the client, has been sentenced to 15 years in prison.

Martha Mata Vasquez, 39, had charged clients up to $1,400 for each injection of Mazola corn oil, claiming the "French polymer" treatment would reduce wrinkles, prosecutors said.

Vasquez, who pleaded no contest in October to involuntary manslaughter, practicing medicine without a license and fraud, apologized during Wednesday's sentencing hearing.

"I'm very sorry to my family, and I'm sorry to them (the victims and their families)," the married mother of two said.

Maria Olivia Castillo, 46, of Castroville, Calif., died in November 2005 of multiple organ failure caused by a fat blockage brought about by a cooking oil injection, prosecutors said. Similar injections caused medical complications for others and put one patient into a coma, prosecutors said.

Defense attorneys said Vasquez did not know of the dangers of the injections.

"That couldn't be farther from the truth," said Deputy District Attorney Steve Somers, noting Vasquez continued to perform the procedure after clients became ill.