George Zimmerman was acquitted over the weekend of second-degree murder and manslaughter charges in Martin's 2012 death in Sanford, Fla. Holder said the Justice Department has an open investigation into what he called Monday the "tragic, unnecessary shooting death" of the unarmed Miami 17-year-old.
He urged the nation then to speak honestly about complicated and emotionally charged issues. A day later, he seemed to shift away from the specific case to one of those issues the debate over stand-your-ground.
"There has always been a legal defense for using deadly force if and the 'if' is important no safe retreat is available," Holder told the NAACP.
The country must take a hard look at laws that contribute to "more violence than they prevent," Holder said during a speech before an NAACP convention in Orlando, about 20 miles from the courthouse where Zimmerman was cleared of the charges three days earlier. Such laws "try to fix something that was never broken," he said.
Martin's shooting shined a light on Florida's stand-your-ground and similar laws around the nation. Most say a person has no duty to retreat if he is attacked in a place he has a right to be and can meet force with force if he fears death or great bodily harm.
Sanford's police chief at the time since replaced had cited the law as his reason for not initially arresting Zimmerman in February 2012. Zimmerman told police Martin was beating him up during the confrontation and that he feared he would be killed.
Though stand-your-ground was never raised during trial, Judge Debra Nelson included a provision about the law in the instructions that allowed jurors to consider it as a legitimate defense.
"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," Holder said.
The defense skipped a chance to ask that Zimmerman have a stand-your-ground hearing before trial. If the judge had decided there was enough evidence that Zimmerman acted in self-defense, she could have tossed out the case before a jury heard it.
"Stand-your-ground laws license vigilantism and we should all worry about that," said Benjamin Jealous, the NAACP's president and CEO, after Holder's speech.
Holder on Tuesday only briefly touched on a possible federal civil rights case being brought against Zimmerman. And legal experts say such a case would be a difficult challenge.
Prosecutors would have to prove that Zimmerman was motivated by racial animosity to kill Martin. The teen was on his way back to his father's fiancee's house after going to a store when the neighborhood watch volunteer saw him and followed him in the community of about 50,000, which is about one-third black.
Civil rights leader Al Sharpton, who has been one of the most vocal champions of a federal investigation, acknowledged Tuesday there are possible legal hurdles. Still, he said "there is also a blatant civil rights question of does Trayvon Martin and the Trayvon Martins of this country have the civil right to go home."
Saturday's acquittal has inspired "Justice For Trayvon" protests around the nation. Most have been peaceful, although vandalism and violence happened in Los Angeles.
Dozens of protesters carrying signs demanding justice for Martin crammed into the lobby of Florida Gov. Rick Scott's office Tuesday and refused to leave until the governor either met with them or called lawmakers back to Tallahassee to address issues like the state's stand-your-ground law. Many planned to spend the night in the Capitol building.
Despite the challenges of bringing a federal civil rights case, some NAACP members said they wanted swift action.
Tony Hickerson, an NAACP member from Seattle, said he would be disappointed if he doesn't see the Justice Department taking action within a month.
"I heard what he (Holder) said, and I don't question his sincerity, but I'd like to see swift action in this case, and I haven't seen that yet," said Hickerson. "His words were eloquent but I need to see some action before I get enthusiastic."
Added Hickerson, "This is a very obvious case. How much thinking do you have to do?"
In his comments referencing the Zimmerman case, Holder offered a story from his own personal experience describing how when he was a young black man his father had told him how to interact with the police, what to say and how to conduct himself if he was ever stopped or confronted in a way he 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," Holder told the NAACP convention. "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."