U.S. Attorney General Eric Holder spoke Tuesday to thousands of attendees at the NAACP Convention in Orlando, just one day after calling Trayvon Martin's death a "tragic, unnecessary shooting."

The NAACP's annual convention runs through Wednesday at the Orange County Convention Center.

Holder said Monday the Justice Department will follow "the facts and the law" as it reviews the evidence in the George Zimmerman case to see whether federal criminal charges are warranted. Zimmerman was found not guilty of second-degree murder Saturday night for shooting and killing Trayvon Martin in 2012.

In his first comments since Zimmerman's acquittal, Holder said Martin's death provides an opportunity for the nation to speak honestly about complicated and emotionally charged issues. He said the nation must not forgo an opportunity toward better understanding of one another.

"I hope that we will approach this necessarily difficult dialogue with the same dignity that those who have lost the most, Trayvon's parents, have demonstrated throughout the last year, and especially over the past few days," Holder said. "They suffered a pain that no parent should have to endure, and one that I, as a father, cannot begin to conceive."

Hundreds of students attended an event Monday at the NAACP convention, many saying they were upset by the not guilty verdict, but were ready to channel their energy into political action to change the criminal justice system.

"We must begin to mobilize young people to go to the polls, as well as begin to have positive solutions about race in this country," said Stephen Green, of Orlando. "That is something very critical that we have failed to have a positive nationwide conversation about race and be relevant."

The Justice Department is examining evidence in the case and testimony from the state trial to determine whether criminal civil rights charges would be brought. However, legal experts said Justice officials would likely be saddled with some of the same challenges that complicated the unsuccessful state case. The key to charging Zimmerman lies in whether evidence exists that he was motivated by racial animosity to kill Martin.

"There is a federal prosecution that theoretically is possible, but I'm sure federal prosecutors would think long and hard, given the state of the evidence, whether they would try to pursue that," said Scott Sundby, a former federal prosecutor who teaches criminal law at the University of Miami law school. "You'd have to prove that George Zimmerman was seeking out to commit the crime against Trayvon Martin, specifically because he was African-American."

President Barack Obama won't involve himself in the Justice Department's decision on whether to pursue a civil rights case because it would be inappropriate for the president to express an opinion on how the department deals with Zimmerman, White House press secretary Jay Carney said Monday.

Zimmerman, 29, was acquitted of second-degree murder and manslaughter charges Saturday by a jury in Seminole County after claiming he fired his weapon in self-defense only after Martin attacked him. No evidence surfaced in the trial that Zimmerman had a racial bias, and his friends and family have repeatedly denied he harbored racial animosity toward blacks. Florida did not use its own hate crime laws against Zimmerman.

Holder's comments on the case came in a speech to the 51st national convention of the Delta Sigma Theta, the nation's largest African-American sorority, and drew strong applause with his characterization of the shooting: "We are … mindful of the pain felt by our nation surrounding the tragic, unnecessary shooting death of Trayvon Martin."

Martin's family and supporters maintain that Zimmerman racially profiled Martin and decided to follow him, leading to the fatal fight. Supporters of the Justice Department filing civil rights charges said additional evidence could exist in the federal investigation that didn't come up in the state prosecution of Zimmerman, possibly even unknown witnesses.

Several civil rights groups, including the NAACP, are demanding that the Justice Department bring federal charges against Zimmerman, and there have been numerous protests around the country about the outcome of the Florida trial. Beyond the exact language of the law itself, the federal probe must navigate between sensitive racial and political issues that arose when Zimmerman initially wasn't charged in Martin's killing.

Barbara Arnwine, president and executive director of the Lawyers Committee for Civil Rights Under Law, called the verdict "a travesty and miscarriage of justice" and urged the Justice Department to bring criminal civil rights charges against Zimmerman.

Zimmerman could get life in prison if charged and convicted under federal hate crime laws.

Several former prosecutors said they'd be surprised if the department were to charge Zimmerman under civil rights laws.

"I think it would be a very steep, if not insurmountable, hill to climb and would be shocked to see any further DOJ involvement," said Jeffrey Sloman, former U.S attorney in Miami.

Sundby said the legal system does not always provide an outcome that satisfies people who believe Martin's killing was unjustifiable and morally wrong.

"That's frustrating as a lawyer to say, but sometimes the legal system - even if there's a sense that an injustice was done - it doesn't have an answer to that injustice," he said.

Full text of Attorney General Eric Holder's speech:

Thank you, Derrick [Johnson], for those kind words – and thank you all for such a warm welcome. It’s a pleasure to be in Orlando today. And it’s a privilege to join President [Ben] Jealous, Chairman [Roslyn] Brock, your National Board of Directors – and my good friends Secretary [Shaun] Donovan and Secretary [Kathleen] Sebelius – in celebrating the NAACP’s 104th Annual Convention, and recommitting ourselves to your important work.

I’m proud to be in such good company this afternoon – among so many friends, courageous civil rights leaders, and passionate men and women who have dedicated themselves to bringing our nation together, addressing common challenges, and focusing attention on the problems and inequities that too many of our citizens continue to face.

Even as this convention proceeds, we are all mindful of the tragic and unnecessary shooting death of Trayvon Martin last year – in Sanford, just a short distance from here – and the state trial that reached its conclusion on Saturday evening. Today, I’d like to join President Obama in urging all Americans to recognize that – as he said – we are a nation of laws, and the jury has spoken. I know the NAACP and its members are deeply, and rightly, concerned about this case – as passionate civil rights leaders, as engaged citizens, and – most of all – as parents. This afternoon, I want to assure you of two things: I am concerned about this case and as we confirmed last spring, the Justice Department has an open investigation into it. While that inquiry is ongoing, I can promise that the Department of Justice will consider all available information before determining what action to take.

Independent of the legal determination that will be made, I believe this tragedy provides yet another opportunity for our nation to speak honestly – and openly – about the complicated and emotionally-charged issues that this case has raised.

Years ago, some of these same issues drove my father to sit down with me to have a conversation – which is no doubt familiar to many of you – about how as a young black man I should interact with the police, what to say, and how to conduct myself if I was ever stopped or confronted in a way I thought was unwarranted. I’m sure my father felt certain – at the time – that my parents’ generation would be the last that had to worry about such things for their children.

Since those days, our country has indeed changed for the better. The fact that I stand before you as the 82nd Attorney General of the United States, serving in the Administration of our first African American President, proves that. Yet, for all the progress we’ve seen, recent events demonstrate that we still have much more work to do – and much further to go. The news of Trayvon Martin’s death last year, and the discussions that have taken place since then, reminded me of my father’s words so many years ago. And they brought me back to a number of experiences I had as a young man – when I was pulled over twice and my car searched on the New Jersey Turnpike when I’m sure I wasn’t speeding, or when I was stopped by a police officer while simply running to a catch a movie, at night in Georgetown, in Washington, D.C. I was at the time of that last incident a federal prosecutor.

Trayvon’s death last spring caused me to sit down to have a conversation with my own 15 year old son, like my dad did with me. This was a father-son tradition I hoped would not need to be handed down. But as a father who loves his son and who is more knowing in the ways of the world, I had to do this to protect my boy. I am his father and it is my responsibility, not to burden him with the baggage of eras long gone, but to make him aware of the world he must still confront. This is a sad reality in a nation that is changing for the better in so many ways.

As important as it was, I am determined to do everything in my power to ensure that the kind of talk I had with my son isn’t the only conversation that we engage in as a result of these tragic events.

In the days leading up to this weekend’s verdict, some predicted – and prepared for – riots and waves of civil unrest across the country. Some feared that the anger of those who disagreed with the jury might overshadow and obscure the issues at the heart of this case. But the people of Sanford, and, for the most part, thousands of others across America, rejected this destructive path. They proved wrong those who doubted their commitment to the rule of law. And across America, diverse groups of citizens, from all races, backgrounds, and walks of life, are instead overwhelmingly making their voices heard – as American citizens have the right to do – through peaceful protests, rallies, and vigils designed to inspire responsible debate – not incite violence and division; and those who conduct themselves in a contrary manner do not honor the memory of Trayvon Martin.

I hope that we will continue to approach this necessarily difficult dialogue with the same dignity that those who have lost the most – Trayvon’s parents – have demonstrated throughout the last year – and especially over the past few days. They suffered a pain that no parent should have to endure – and one that I, as a father, cannot begin to conceive. As we embrace their example – and hold them in our prayers – we must not forego this opportunity to better understand one another. And we must not fail to seize this chance to improve this nation we cherish.

Today – starting here and now – it’s time to commit ourselves to a respectful, responsible dialogue about issues of justice and equality – so we can meet division and confusion with understanding, with compassion, and ultimately with truth.

It’s time to strengthen our collective resolve to combat gun violence but also time to combat violence involving or directed toward our children – so we can prevent future tragedies. And we must confront the underlying attitudes, mistaken beliefs, and unfortunate stereotypes that serve too often as the basis for police action and private judgments.

Separate and apart from the case that has drawn the nation’s attention, it’s time to question laws that senselessly expand the concept of self-defense and sow dangerous conflict in our neighborhoods. These laws try to fix something that was never broken. There has always been a legal defense for using deadly force if – and the “if” is important – no safe retreat is available.

But we must examine laws that take this further by eliminating the common sense and age-old requirement that people who feel threatened have a duty to retreat, outside their home, if they can do so safely. By allowing and perhaps encouraging violent situations to escalate in public, such laws undermine public safety. The list of resulting tragedies is long and – unfortunately – has victimized too many who are innocent. It is our collective obligation – we must stand our ground – to ensure that our laws reduce violence, and take a hard look at laws that contribute to more violence than they prevent.

We must also seek a dialogue on attitudes about violence and disparities that are too commonly swept under the rug – by honoring the finest traditions established by generations of NAACP leaders and other nonviolent advocates throughout history; and by paying tribute to the young man who lost his life here last year – and so many others whose futures have been cut short in other incidents of gun violence that pass, too often unnoticed, in our streets: by engaging with one another in a way that is at once peaceful, inclusive, respectful – and strong.

As we move forward together, I want to assure you that the Department will continue to act in a manner that is consistent with the facts and the law. We are committed to doing everything possible to ensure that – in every case, in every circumstance, and in every community – justice must be done.

For more than a century – since this organization was founded, in 1909 – the NAACP has led efforts to do just that, standing on the front lines of our fight to ensure security, opportunity, and equal treatment under law. Especially in times of need and moments of danger, you have dared to seek opportunities for progress and growth – challenging this nation to aim higher, to become better, and to move ever closer to its founding ideals.

Under the banner of the NAACP, courageous men and women like W.E.B. DuBois, Walter White, Charles Hamilton Houston, Ida B. Wells, Rosa Parks, Martin Luther King, Jr. – and countless others whose names may be less familiar, but whose contributions are no less important – have raised their voices, and too often given their lives, to advance our common pursuit of a more perfect Union. Their stories prove that today’s civil rights leaders can best honor the progress of the last century by planning for the challenges of the next. Their examples remind us that – as recent events illustrate – our work is far from over. And it’s time to acknowledge, once again, that we have much more to do.

After all, we come together today in another moment of need, during a year defined by historic milestones – including, just last month, the 50th anniversary of the infamous “Stand in the Schoolhouse Door”– when two brave young students enlisted the advice of NAACP lawyers, the support of the Justice Department, and the protection of the National Guard to step past Governor George Wallace and integrate the University of Alabama.

One of those students, Vivian Malone, would much later become my sister-in-law. Although she passed away several years ago – much too soon – her courage made a strong impression on me when I was a young man. Her story, and others like it, drove me to dream of a career in public service – and led me to spend my first summer in law school working for the NAACP’s Legal Defense Fund. And her memory inspires me to think often of the historic speech that President John F. Kennedy delivered on that fateful night – 50 years ago last month – when he addressed the American people; expressed his support for Vivian and her classmate, James Hood; and described the cause of civil rights as a “moral issue” that is “as old as the scriptures and . . . as clear as the Constitution.”

In that extraordinary moment, President Kennedy urged his fellow citizens to refuse to accept that anyone could be denied opportunity, denied education, or denied the future of their choosing just because of the color of their skin. And he called on Congress to pass sweeping civil rights legislation – outlining a series of proposals that would later be included in the Civil Rights Act of 1964 and the landmark Voting Rights Act of 1965.

Once signed into law by his successor, President Lyndon Johnson, these proposals affirmed – and codified into law – the greatest of American ideals: that all are created equal. They established protections for the rights to which every citizen, and every eligible voter, is entitled. And they came to represent nothing less than the foundation of modern civil rights law.

Unfortunately, last month, an important piece of this foundation was chipped away – when the Supreme Court invalidated a key part of the Voting Rights Act.

Over the years – and in the past 18 months – this provision, called pre-clearance, allowed the Department to take swift action against numerous jurisdictions that adopted rules or procedures with either a discriminatory purpose or effect. It served as a potent tool for addressing inequities in our elections systems. And it proved the effectiveness of a legal mechanism that puts on hold any new voting changes until they have been subjected to a fair, and thorough, review.

Let me be clear: this was a deeply disappointing and flawed decision. It dealt a serious setback to the cause of voting rights. And, like all of you, I strongly disagree with the Court’s action.

After all, as we’ve seen over the last 18 months, numerous successful decisions in the Department’s Voting Rights Act cases have proven that – far from being an antiquated relic of a bygone era – such a process frequently resulted in approvals for fair and impartial voting changes, while allowing the Department to work with jurisdictions to address problems wherever they occur.

For instance, just last year, a federal court noted the “vital function” that preclearance played in protecting black voters who would have been disproportionately impacted by a photo ID law in South Carolina. Because of the Department’s engagement with the state during the administrative review and later litigation, South Carolina officials changed how their new voting statute will be implemented in future elections – to eliminate what would otherwise have been a dramatic discriminatory effect. Another court cited the Voting Rights Act in blocking a Texas congressional redistricting map that would have discriminated against Latino voters – noting that the parties “provided more evidence of discriminatory intent than we have space, or need, to address here.”

These cases, and many others, illustrate that these problems are real. They are significant. They corrode the foundations of our democracy. And they are of today – not yesterday. In fact, despite last month’s ruling, every member of the Supreme Court has agreed that – as the Chief Justice wrote, “voting discrimination still exists: no one doubts that.” Therefore, the struggle for voting rights cannot be relegated to the pages of history. And this is why protecting the fundamental right to vote – for all Americans – will continue to be a top priority for the Department of Justice so long as I have the privilege of serving as Attorney General.

It’s also why – although I remain disappointed with this outcome – I believe we must regard it not as a defeat, but as a rare and historic opportunity: for Congress to consider new legislation restoring and even strengthening modern voting protections – in a manner that’s consistent with the record established by one of the most effective civil rights laws in American history.

After all, in the nearly half-century since its passage, the Voting Rights Act enjoyed broad, bipartisan support on Capitol Hill as well as in the executive branch. Its most recent reauthorization passed Congress with near-unanimous support in 2006, and was signed into law by President Bush – just as prior reauthorizations had been signed by Presidents Reagan, Ford, and Nixon.

This is because providing fair and equal access to the ballot box has never been a partisan issue. It’s an American issue. It’s about the core values that define us as a nation – and who we say we are as a people.

Whatever solutions our Congressional leaders consider, I urge them to bear in mind – as they move forward – that the right to vote is both a guarantee and a sacred duty, conferred by citizenship and protected by the United States Constitution. Quite simply, Congress must take steps to ensure that every eligible American has equal access to the polls.

In the meantime, the Justice Department will continue to monitor jurisdictions around the country for any changes that may hamper voting rights. We will not hesitate to take aggressive action – using every tool that remains available to us – against any jurisdiction that attempts to take advantage of the Supreme Court’s ruling by hindering eligible citizens’ free and fair exercise of the franchise.

We also will not wait for Congressional action to refine – and re-focus – our current enforcement efforts. In fact, I am announcing today that I have directed the Department’s Civil Rights Division to shift resources to the enforcement of Voting Rights Act provisions that were not affected by the Supreme Court’s ruling – including Section 2, which prohibits voting discrimination based on race, color, or language – in addition to other federal voting rights laws.

It is clear that our work is anything but complete. Our cause is not yet fulfilled. And, for all the progress we’ve made over the last 104 years – our nation’s journey along the road to equality and opportunity is far from over.

This journey goes on every day in the efforts of those who seek to extend the legacy that our predecessors have established – by combating violence and realizing America’s founding, and enduring, promise of equal justice under law. It goes on in the steadfast commitment of my colleagues throughout the Justice Department – and the entire Obama Administration – to prevent all types of civil rights violations. Most of all, it goes on in the passionate advocacy of concerned, dedicated, and ultimately hopeful men and women in – and far beyond – this room: the members and leaders of America’s oldest and largest civil rights organization.

Make no mistake – the NAACP’s work is not just historically relevant. It is, and will always be, a vital and contemporary part of what makes this country truly exceptional.

So let us pledge that we will honor heroes like Dr. King, Medgar Evers, Vivian Malone – and so many others who have struggled, sacrificed, and died for the freedoms we now enjoy – by zealously guarding the progress they achieved, and matching their contributions with our own.

Above all, let us act – with optimism, and without delay – to seize the breathtaking opportunities now before us. To see that justice is done, and strengthen our nation’s long tradition of increasing opportunity and inclusion. And to continue the work that constitutes our shared purpose, and must always remain our common cause: the enduring pursuit of a more equitable, more just, and more perfect Union.

Thank you.