Fairfax County Sheriff Stacey Kincaid. (Eva Russo/For The Washington Post)

NATASHA McKENNA, the schizophrenic woman who died in February after Fairfax County jail guards shot her four times with a Taser, should not have been behind bars. She should have been in treatment at a facility staffed with mental health professionals.

Some county officials have acknowledged that; they include Sheriff Stacey A. Kincaid, who runs the jail, where some 40 percent of the 1,100 inmates suffer from mental illness or substance addiction. Now it’s time for Fairfax, whose 1.1 million people make it more populous than all but nine U.S. cities, to make reforms to ensure that senseless tragedies like Ms. McKenna’s death do not recur.

The question is whether county officials — not just Ms. Kincaid, but also prosecutors, public defenders, judges, police and others — have the political will to shake up an entrenched system and whether they will find the dollars to do it. It won’t be easy, and it won’t be quick, but failing to act would be a disgrace.

The county has a plan to establish a fledgling program, starting Jan. 1, to divert nonviolent people who have mental illness to a county-run crisis center in Merrifield. Rather than jailing them, police officers, trained to detect the signs of mental health crises, would be able to hand them off to a team of professional staff at the center for evaluation and formulation of a treatment plan.

That sounds simple enough; in fact it will require several million dollars just to inaugurate what amounts to a pilot program — money that would go to training hundreds of cops and sheriff’s deputies as well as to providing the staff to run the center 16 hours a day. At a guess, hundreds, and quite possibly a few thousand, people with mental illness could avoid incarceration annually. Instead they would be channeled into state and private hospitals, facilities and treatment programs, including ones monitored by the courts.

The advantages of such a system are many. One would be better outcomes for mentally ill individuals for whom jail is just a revolving door to trouble. Another would be cost-saving for the county, which could more efficiently deploy police officers and others whose time is now too often monopolized tending to crisis for which they lack adequate training.

There are models elsewhere in the country of programs that have successfully diverted large numbers of people who would otherwise clog the jails. One is in Bexar County, Tex., which includes San Antonio. There, officials estimate that the county saves several million dollars annually as a result of decreasing the jail’s inmate population and hospital emergency room admissions.

Last spring, Fairfax applied for a $1.5 million state grant to establish a diversion program, but officials in Richmond determined that the county had not laid the necessary groundwork — establishing policies and coordination among various agencies — to implement the program. The county has gone back to the drawing board and allotted $400,000 of its own funds to get the pilot program rolling next year.

That’s a start, but it is a modest one. It remains to be seen whether circuit court judges, prosecutors and other leaders will play ball, which will be necessary to design and implement a full-fledged program to get mentally ill individuals the care and monitoring they desperately need.