GEOFF BENNETT: Shifting our focus now to a gruesome murder in Charlotte, North Carolina, last month that claimed the life of a young Ukrainian refugee and has become a rallying cry for Republicans.

They argue Democrats are soft on crime and they point to the killing to support President Trump's decision to deploy the National Guard in more cities.

Our William Brangham has the latest.

WILLIAM BRANGHAM: The security camera video from the Charlotte light rail system is very hard to watch, and we're not going to show it in full; 23-year-old Iryna Zarutska boards a train after work and takes a seat.

Behind her in the red hoodie is Decarlos Brown Jr., who authorities say was homeless and mentally ill. Brown opens a pocket knife, gets up, and stabs Zarutska in the neck.

She had fled Ukraine after Russia's invasion and settled in North Carolina.

She died on the spot.

Brown was charged in federal court today.

According to authorities, he had previously spent time in prison for robbery and had repeatedly shown troubling, erratic behavior, from attacking and biting his sister to calling police saying he was being controlled by some manmade substance.

His mother told local news that he was schizophrenic.

This horrible crime has now been seized on by Republicans to depict Democratic-run cities like Charlotte as being plagued by widespread violence and mayhem.

Charlotte's police say violent crime so far this year is down 25 percent compared to last year.

Many Republicans, all the way up to the president, have blamed Democrats for this murder.

President Trump posted this today: DONALD TRUMP, President of the United States: For far too long, Americans have been forced to put up with Democrat-run cities that set loose savage, bloodthirsty criminals to prey on innocent people.

WILLIAM BRANGHAM: For more on this case, we are joined by writer Alisa Roth.

She's author of the book "Insane: America's Criminal Treatment of Mental Illness."

Alisa, thank you so much for being here.

We should say at the outset that the data show that people suffering from mental illness are much more likely to be victims of violence than perpetrators of it.

But when a case like this occurs, where the reverse happens, what is your initial reaction?

ALISA ROTH, Author, "Insane: America's Criminal Treatment of Mental Illness": My initial reaction is that this is a tremendous tragedy.

And it's a tragedy for everybody involved.

It's obviously a terrible, terrible tragedy for Ms. Zarutska and her family.

It's also a tragedy for Mr. Brown.

He's clearly a person who's in desperate need of help.

He's a person who knew he needed help.

He called the police asking for help, and he didn't get it.

And so it's really a tragedy all around.

WILLIAM BRANGHAM: I mean, his life trajectory, as far as we know it, shows that he repeatedly interacted with the police, with the courts, with hospitals.

And despite showing increasingly erratic and troubling behavior, "the system" -- quote, unquote -- kept putting him back out on the street.

How common is his example in our society?

ALISA ROTH: Unfortunately, it's very, very common.

People -- a person with mental illness will get arrested, often for a low-level crime, often for a crime of survival.

So they might be, as Mr. Brown was, homeless.

So you get arrested for sleeping on the street or for stealing food.

They get arrested.

They get taken to jail.

They may even serve some small amount of jail time, get, if they're lucky, a little bit of mental health care in jail or in prison if things get that far.

And then they're released because they have done their time, but we haven't addressed any of the underlying problems, whether that's the mental illness or whether it's the other societal issues of homelessness and not having enough food and all these things.

And, of course, often all those things go together, complicating it.

WILLIAM BRANGHAM: I mean, the Republican Party, writ large, right now is trying to portray this as this is evidence of Democratic policies, that Democrats want to coddle people like Mr. Brown, rather than lock him up or to really take care of him.

How fair is that characterization?

ALISA ROTH: I think the real question is, what works?

We know that putting people with mental illness into the criminal justice system, so into jail or into prison, doesn't help.

They're getting at best minimal mental health care.

They're often coming out of jail or prison in worse shape than they went in even.

And it's, again, not solving the underlying problems.

So I don't think it's even a question of, are we being too nice?

We're doing something that's very, very expensive, very, very difficult for everybody involved.

And we're not making anything any better.

WILLIAM BRANGHAM: There are a growing number of cities and states that, faced with incidents like this, are turning to what's called involuntary commitment, where a judge basically says, you need mental health care, whether you want it or not, and forces you into some kind of a facility.

How good of a solution is that?

ALISA ROTH: In the very short term, it can be useful.

One of the many complicating factors of mental illness is that it is obviously a disease of the brain, which means that sometimes a person with mental illness won't realize they're sick or they won't realize how sick they are.

And so sometimes somebody else needs to step in and say, you need to go to the hospital, you need to get better.

But we obviously also don't want a society where we're locking people up indefinitely because they have mental illness.

And so there needs to be a larger system, a larger mental health care system that's actually dealing with the underlying problems and that's helping continue that mental health care once the person is released from that involuntary commitment.

WILLIAM BRANGHAM: All right, that is journalist Alisa Roth, author of "Insane: America's Criminal Treatment of Mental Illness."

Alisa, thank you so much for being here.

ALISA ROTH: You're welcome.