Three strangers saved her and her friend’s life — and two of them died in doing so.

On Friday, 16-year-old Destinee Mangum and her 17-year-old Muslim friend, who was wearing a hijab, were on a Portland, Oregon, light-rail train when a man — now identified as 35-year-old Jeremy Joseph Christian — yelled what police described as “hate speech toward a variety of ethnicities and religions.” Mangum and her friend moved away from the man, fearing for their lives.

Strangers intervened, telling the man he couldn’t disrespect the girls like that. What started as an argument suddenly turned violent, however, as Christian allegedly began stabbing people.

Ricky John Best, a 53-year-old military veteran, and Taliesin Myrddin Namkai-Meche, a 23-year-old who graduated from Reed College last year, died as a result of their wounds. Micah Fletcher, 21, is being treated at a hospital after he was seriously injured, according to CNN.

In an interview with local news station Fox 12, Mangum’s mother, Dyjuana Hudson, thanked the people who protected her daughter. “I want to say thank you so much,” she said. “I couldn’t imagine what you’re going through right now as far as losing someone.”

Christian, meanwhile, was caught after several people chased after him and called 911, directing police to him. He’s charged with two counts of aggravated murder and one count of attempted murder.

It’s unclear if Christian will be charged with a hate crime, but he has a history of racist actions. Police said he went on a racist tirade on a train the day before the attack, but nothing was done about that incident. On his Facebook page, he appeared to support Nazis and Oklahoma City bomber Timothy McVeigh, according to CBS News.

The attack is particularly awful as it comes during the beginning of Ramadan, the Muslim holy month.

More broadly, it’s just the latest act in what seems like a wave of hate crimes following President Donald Trump’s election in November. Trump condemned the Portland attack on Twitter, but his racist, Islamophobic, and anti-immigrant rhetoric on the campaign trail has been widely criticized as a reason for a potential uptick in such bigoted acts.

Earlier in May, Sean Urbanski, who’s white, stabbed and killed Richard Collins, who’s black, at the University of Maryland. And before that, there were reports of mosques being burned, violent attacks against Indians, and a drive-by shooting at the Tulsa, Oklahoma, headquarters for the LGBTQ organization Oklahomans for Equality. Not all of these attacks have been verified as acts motivated by bigotry or directly linked to Trump, but they’re certainly a cause for alarm.

So is America experiencing a rise in hateful attacks? The unsettling truth is we just don’t know — in large part because the US does such a bad job tracking hate crimes nationally that it’s hard to find any good statistics to compare the current figures to. But the numbers we do have suggest that certain groups, particularly Muslims, have faced more hate in the past several years.

Is there a rise in hate crimes in America? We don’t really know.

The latest report from the FBI found that there was a 7 percent rise in reported hate crimes in 2015, driven in large part by a 67 percent rise in reported hate crimes against Muslims. That certainly seems to suggest that there has been an increase.

But the FBI data isn’t very good. For one, the FBI relies on voluntary reports from police departments. So police departments might not report their data on hate crimes — which “manifest evidence of prejudice based on race, gender and gender identity, religion, disability, sexual orientation, or ethnicity” — to the FBI. (A 2016 Associated Press investigation found this is common.) Worse, police departments themselves may not track hate crimes at all, or victims may not report the crimes to the police, leaving departments in the dark.

“You cannot tell if hate crimes are going up year over year from the FBI reports,” Mark Potok, a senior fellow at the civil rights group Southern Poverty Law Center, previously told me. “It is not possible.”

Consider one statistic: Over the past two decades, the FBI reported between 6,000 and 10,000 hate crime incidents each year in the US. But when the US Bureau of Justice Statistics surveyed a large segment of the population between 2007 and 2011 to try to gauge what the real number of hate crimes is, it concluded that there are nearly 260,000 annually. This means that the FBI is potentially undercounting hate crimes by a magnitude of more than 40 times.

“If there are 10,000 hate crimes a year, that’s a lot, but perhaps it’s not a major social problem in a country of 320 million people,” Potok said. “If on the other hand there are a quarter million or even 300,000 hate crimes a year, it begins to look different. It begins to look like maybe we need to take this seriously as a society and put serious resources toward it.”

The Bureau of Justice Statistics also found that only 35 percent of hate crimes are ultimately reported to the police, meaning that cops are unaware of roughly two-thirds of hate crimes in their communities.

There are some problems with the BJS data. For one, it relies solely on victims’ reports of offenses against them, so the reports aren’t fully verified. It also only counts nonfatal hate crimes, since victims of fatalities obviously can’t report a crime. So it’s likely overestimating some hate crimes and underestimating others.

But the BJS also doesn’t do its hate crime report every year — leaving it solely to the FBI to find out and report what’s happening on an annual basis.

Potok said it’s probably possible to draw some inferences from within the FBI data. For example, since the number of anti-Muslim hate crimes rose by so much in proportion to all hate crimes, there probably is something going on there. But it’s hard to say what the exact depth of the problem is without more accurate figures.

This, obviously, presents a big hurdle to preventing hate crimes. The first thing you need to know to fix a problem is what, exactly, the problem is. We don’t even know for sure, at least on a yearly basis, how many hate crimes there are in America. But we also don’t know where the attacks are happening or who’s targeted.

At the very least, it seems like getting the Bureau of Justice Statistics to conduct its report on hate crimes annually, much like it does for crime overall, would be a good start. But it also seems like this is something police departments should take more seriously, in terms of both seeking out and preventing potential hate crimes in their communities and reporting what they find to the FBI.

Prosecuting hate crimes is fairly difficult

Even when a victim does report a hate crime, it can be fairly difficult for police and prosecutors to prove the charges.

The first big question is whether your state actually has a hate crime law. The federal government has a hate crime law that bans crimes based on race, color, religion, national origin, gender, sexual orientation, gender identity, or disability, but some places don’t have such laws at the state level. That presents a major challenge: While the federal government will take on some of these cases, it doesn’t have the resources to enforce its law against all hate crimes nationwide — so a gap in state laws means some hate crimes will go unpunished.

If a state does have a hate crime law or federal law enforcement gets involved in a case, the important thing here is that someone must commit an actual crime to be charged with a hate crime. That crime can then be elevated to a hate crime if there’s enough evidence to suggest that the motive for the act was hate. But if no crime was committed in the course of someone doing something hateful, it’s a hateful act, but not a hate crime.

“It could be an act of trespassing or vandalism. It could be a violent crime, like rape or murder,” Jack Levin, an expert on hate crimes at Northeastern University, previously told me. “But when the motive involves targeting someone because of a difference, then it becomes a hate crime.”

An example: A man walks into a lesbian bar and attacks one of the women there. This attack would be considered assault and battery, maybe even attempted murder, under the law.

But would it be a hate crime? For a prosecutor and police officers, there would be several factors to consider before going after the perpetrator on hate crime charges: Did the attacker yell anti-gay or sexist slurs, or otherwise say anything explicitly anti-gay or sexist? Does the attacker have a history, perhaps on social media or in other writings, of homophobia or sexism? Did the attacker purposely target a lesbian bar, or was the location irrelevant to his actions?

Investigators would piece all of this together, building up evidence to decide if there’s enough to meet standards of proof for a hate crime charge and conviction. There’s no hard rule here, and whether something is deemed a hate crime can vary from officer to officer, prosecutor to prosecutor, judge to judge, or jury to jury. But generally, once there’s a certain threshold of evidence that the attack was motivated by hate, an otherwise run-of-the-mill crime can become a hate crime.

Now, if a man walked by a lesbian bar and simply yelled anti-gay slurs but didn’t attack anyone, that wouldn’t qualify as a hate crime. His speech, as reprehensible as it may be, would be protected by the Constitution. Until he commits an actual crime, his act can’t be additionally prosecuted as a hate crime.

The idea, essentially, is to take extraordinary steps against crimes that can go much further than harming individual victims. “If someone assaults me because they want my money, it’s going to affect me, it’s going to affect my wife, it’s going to affect my family,” Toni Bisconti, a University of Akron professor who studies hate crimes, previously told me. “But if someone assaults me because they know I’m gay, then all of a sudden it’s going to affect people that don’t even know me. They have no idea who I am. I’m just the conduit to gay people [in that situation].”

The focus on motives in these cases can get into some legally and philosophically murky territory: Does focusing so much on what’s in a criminal’s mind allow the government to regulate a person’s free speech and expression?

Bisconti acknowledged that such a concern has some merit. Although she said she probably comes down in support of hate crime laws, she acknowledged, “I’m not sure it’s right to legislate someone’s brain.”

Jeannine Bell, a scholar on hate crimes at Indiana University’s Maurer School of Law, took a different view, arguing that it’s not really about a person’s speech or ideas but the person’s actions. “It’s not just that you dislike people of my background. You’re entirely free to dislike people of my background. It’s not that you tell me that you don’t like me. Again, entirely free to do that,” Bell said. “It’s that you selected me for some sort of criminal action because of my background.”

Whatever one’s view on this debate, the central focus of hate crimes — what elevates them above other crimes — is the criminal’s motive.

Hate crime laws send a countermessage to bigotry

But do hate crime laws actually deter hateful acts?

Every hate crime expert I spoke to agreed that hate crime laws probably don’t deter any crimes. And they said there’s no good research settling this question one way or the other.

“I don’t think that perpetrators think about whether they’re going to commit a hate crime, look to see whether there’s a law that can be punished, and then don’t commit the hate crime when they learn it could be punished,” Bell said. “That doesn’t make sense to me.”

But to my surprise, experts said it doesn’t matter if hate crime laws actually deter crime.

For one, hate crime laws do more than just enhance criminal penalties for committing otherwise typical criminal acts. They often devote funds to police departments — so they can, for example, set up an LGBTQ liaison who works closely with the community to ensure people feel safe. They also label these acts as a very specific kind of vile crime, encouraging law enforcement to take the issue more seriously.

“By making it a hate crime, you call attention to it in the minds of police [and] in the minds of prosecutors,” Bell said. She said, for instance, that most hate crimes are low-level — the kinds of crimes that police and prosecutors may not pay attention to. But once these low-level acts are defined as hate crimes, then they get attention.

Bisconti agreed: “Hate crime legislation allowed groups that don’t feel safe with police officers to come forward, and for police officers to understand that this really is a group that’s targeted.”

More broadly, hate crime laws also send societal signals against hate. Hate crimes are, experts said, message crimes against certain groups of people. Hate crime laws act as a countermessage to that bigotry.

“Hate crime laws have important symbolic meaning,” Levin said. “Hate crimes are message crimes — that is, they send a message not only to the primary victim but to every member of this group.” He added, “That’s the kind of message that has to be counteracted. And I think hate crime laws do that. They send a message to two groups: They send it to the perpetrator, informing him that our community will not tolerate his intolerance. And then at the same time, they send a message to potential victims that they are welcome in our community.”

To the extent that hate crime laws increase prison sentences, some of the experts I spoke to didn’t see much of the value in the enhanced penalties.

Levin, for one, cited the empirical evidence against expanding prison sentences. The research suggests that severity of punishment doesn’t do much to prevent crime. As the National Institute of Justice concluded in 2016, “Research shows clearly that the chance of being caught is a vastly more effective deterrent than even draconian punishment. … Research has found evidence that prison can exacerbate, not reduce, recidivism. Prisons themselves may be schools for learning to commit crimes.”

In other words, more certainty of punishment can deter crime, while more severity — through longer prison sentences — can actually make crime worse.

Generally, though, experts said that hate crimes serve a purpose even if they don’t do much to actually deter crime — by giving marginalized communities resources to fight back and sending a message to criminals that bigotry isn’t accepted.

Following the Portland attack and Trump’s election, some communities are finding those protections, however limited, more necessary.