"The problem that we had is that the receiver was not accountable to anybody," said former state Sen. George Runner, a Republican who has frequently criticized the program.
"So the receiver could just do or choose to spend whatever amount of money he thought was necessary to solve his problem, and unfortunately now the state is stuck with that," he said.
The receiver for medical care, J. Clark Kelso, said the state has been free to collectively bargain health care providers' salaries since a court order increasing their wages expired three years ago.
The receiver's goal was to correct a prison medical system that was ruled unconstitutional for its substandard care and, at one point, contributed to an inmate death each week through negligence or malfeasance.
To do that, the receivership increased salaries, created new positions at high pay and hired hundreds of employees to fill longtime vacancies.
Total spending on medical, dental and mental health care for inmates, numbering 124,700, has more than doubled over the last decade, from $1.1 billion in fiscal year 2003-04 to a projected $2.3 billion this year.
The number of medical, mental health and dental workers in the prisons more than doubled over six years, from 5,100 in 2005, the year before the receivership was created, to 12,200 last year.
More than 1,400 were administrators who don't directly treat inmates, according to a state Assembly oversight committee.
Dr. David M. Mathis at the California Medical Facility in Vacaville, between Sacramento and San Francisco, was paid about $410,000 last year, the most of any prison doctor.
Mathis treats some of the sickest inmates and is the acting medical director at the prison hospice, where terminally ill prisoners go to die. He is a board certified physician who had a solo practice for 25 years.
In addition to his $239,572 base salary, Mathis was paid $169,548 for working nights and weekends. His pay topped other doctors because he also worked overnight, weekend and holiday shifts 10 to 15 times a month.
Prison doctors said they deserve higher pay because they face the constant threat of assault from inmates and because prisons, generally, are located in the most remote regions of the state.
"We're doing it well now because we've got better docs who are willing to work in these less-than-ideal situations and are being adequately compensated," said Mathis, who also worked in prisons in Maryland.
Nancy Kincaid, a spokeswoman for the federal receiver, said paying doctors to work nights and weekends is cheaper than hiring additional doctors with full salaries and benefits.
The state has cut its costs for outside medical care in half by having more sick inmates treated by the prison doctors instead of being sent to hospitals. That also reduces the cost of transporting and guarding them while they are treated outside of the prison.
"I can save the taxpayer a lot of money by coming in to handle things," said Dr. Vache Chakmakian, who works 90 miles from Ironwood State Prison near Blythe, a southern desert city.
Chakmakian was paid $358,645 last year — his regular pay of $239,572 plus $119,072 for frequently working overnight and holidays.
The federal judges and receivers who oversee medical and mental health care said boosting pay significantly was the only way to attract quality employees to such jobs.
One result is that of the top 100 highest-paid state employees outside the University of California system last year, 44 worked in the prisons, according to an Associated Press analysis of state payroll data.
They averaged nearly $379,000 in salary and were led by the $803,271 paid to a psychiatrist at Salinas Valley State Prison.
Base salaries for prison psychiatrists range from $126,000 to $281,952, depending on seniority and other factors, with chief psychiatrists paid more. Dentists' salaries can be as high as $288,000
Compared with the other most populous states, California had higher base salaries for prison doctors than New York, Florida and Pennsylvania.
But base salaries for prison doctors were higher in Texas, particularly when salaries were adjusted for California's higher cost of living, according to a state Department of Finance report.
The prison receiver does not control mental health or dental care, but the finance department counts those in the overall cost of providing inmate medical care, which has risen from $7,747 per inmate the year before the federal receivership began to more than $18,000.
The courts have directed the receivership to wind down while ensuring the state prison system maintains adequate health care for inmates.
The order reignited a debate between Kelso and Gov. Jerry Brown, who has fought the receiver's efforts to provide what the governor once derided as "Cadillac care" for convicts.