Nabra Hassanen's murder highlights the challenges of designating a crime a hate crime

Her father says her murder has all the hallmarks of a hate crime. Police and prosecutors say it was road rage, not religion, that spurred the deadly attack on the Muslim teen.

Nabra Hassanen was beaten to death with a baseball bat -- and her body thrown into a pond -- by a man who police say got into an argument with her and her friend as they headed back to a mosque in Virginia.

Thousands have signed a petition calling on state and federal officials to investigate the 17-year-old's death as a hate crime. But the case, like others before, highlights how challenging it is to apply that label and the narrow criteria it needs to meet.

First, let's consider what's a hate crime?

Virginia law defines a hate crime, in part, as a criminal act committed with the intention of instilling fear in someone because of his or her race, religion or ethnic origin. The FBI's definition is a little broader -- it takes into account the same intent but also includes disability, sexual orientation, ethnicity, gender, or gender identity.

The commonality is this: For a crime to be a hate crime, it has to strike at the heart of one's identity.

"They strike at our sense of self, our sense of belonging," then-FBI Director James Comey said in a speech to the Anti-Defamation League in 2014. "The end result is loss: loss of trust, loss of dignity and, in the worst case, loss of life."

Why do Nabra's parents say it's a hate crime?

People commit hate crimes, experts say, for four main reasons:

They're seeking a thrillThey're "defending" their turf, which can be a neighborhood, a religion or a countryThey're seeking revengeThey consider themselves "crusaders," often for a racial or religious cause.

Nabra's father, Mahmoud Hassanen, says the teen's murder qualifies because it was motivated by racism. "Getting killed because she's Muslim," he told CNN. Nabra was wearing an abaya, a traditional black cloak, and walking back to her mosque with her friends early Sunday morning when the suspect accosted her.

Why do police say it's not?

Because "nothing indicates that the crime was motivated by hate or bias," says Tawny Wright, a spokeswoman with Fairfax Police Department.

"Everyone looks at this crime and thinks that because the victims were participating in activities at a mosque, they assume that's what it was," she told CNN.

But that's not the case, she says. The suspect, 22-year-old Darwin Martinez Torres, saw the group walking and riding bicycles in the street and on the sidewalk. He later found the group in a nearby parking lot, chased them on foot with a baseball bat and beat Nabra, police said.

"It seems like a guy got enraged and just went after the victim who was closest to him," Wright said.

Shouldn't that put the debate to rest?

Not exactly.

Just because Torres didn't vocalize a disdain for Muslims, women or both, while allegedly committing a crime, doesn't mean the crime was not motivated by hate, says CNN legal analyst Danny Cevallos.

"With hate crimes, prosecutors use racial epithets that were shouted during the crime as evidence, but it doesn't punish people who were smart enough to keep their mouth shut," he said.

"Hate crime legislation doesn't attack the underlying hatred; it only punishes those who were dumb enough to shout out racial or other epithets. It doesn't eradicate underlying motives of race or gender."

Also, the final decision on what charges to tack on rests with the district attorney's office. And it is yet to make a determination.

"The investigation is ongoing -- who knows what will come up -- so I would be loath to characterize it one way or the other," said Raymond Morrogh, the Virginia Commonwealth's attorney for Fairfax County.

What will it take to prosecute this as a hate crime?

A lot.

Hate crime prosecutions are exceedingly rare. Since the legislation was passed in 2009, only 29 federal hate crimes have resulted in convictions. During that same time period, federal prosecutors turned down 87 percent of hate crime cases.

The biggest reason? Insufficient evidence.

Proving a hate crime is different than proving other offenses, Cevallos says. Traditionally, the law doesn't punish the motive behind a crime since it isn't itself an element of crime.

"To conclude that you robbed a bank, we need only find that you intended to rob a bank," he said. "The prosecution isn't required to prove that you did it because you're greedy, and it's not a defense that you planned to give the money to charity."

But, Cevallos said, "hate crimes deviate from this rule, and make motive an element of a crime," he said. "Hate crimes also isolate and punish hatred -- which is strange, because hatred by itself is perfectly legal."

Could they consider a person's past behavior?

In today's digital age, they could. Prosecutors can dig into a person's history through their social media feeds. Using discriminatory or racist statements or posts can help a prosecutor prove a reoccuring pattern of racism, sexism, anti-Semitism against a defendant.

This crime happened amid an "unprecedented rise in anti-Muslim hate crimes nationwide," says Ibrahim Hooper, spokesman for Council of American-Islamic Relations.

"We've been doing this for a lot of years, and there are not always overt statements of bias made during the crime," he told CNN. "But we firmly believe that many of these crimes would not have occurred at all if the victims were not perceived as being Muslim."

So, what's the take away?

The takeaway is, it's easier -- relatively speaking -- to secure a conviction on just a murder charge. Trying to prove it's also a hate crime puts more responsibility on prosecutors, who already must prove guilt beyond a reasonable doubt.

"We already have a system that punishes bad crimes and makes the distinction at sentencing," Cevallos said.

"The hate crime legislation will get him a few more years in prison, but is it worth the cost of having to prove? I don't know, but as a society, we've decided that it is worth it."

Brian Levin, director at the Center for the Study of Hate and Extremism, agreed.

Most crimes are not prosecuted as hate crimes because there's rigorous standard that must be met. The hate crime designations work best for prosecutors trying property crimes or non-violent crimes because it takes less to prove beyond a reasonable doubt.

"Abstract beliefs alone," he said, "are not enough to convict someone of a capital offense."