Trayvon Martin, an unarmed 17-year-old, was fatally shot on Feb. 26 in Sanford, Fla. The next day his death was a top story on the Fox-affiliated television station in Orlando, the closest big city to Sanford. By the weekend it was being covered by newspapers across the state.


But it took some time before the rest of the country found out.


It was not until mid-March, after word spread on Facebook and Twitter, that the shooting of Mr. Martin by George Zimmerman, 26, was widely reported by the national media, highlighting the complex ways that news does and does not travel in the Internet age.


That Mr. Martin’s name is known at all is a testament to his family, which hired a tenacious attorney to pursue legal action and persuade sympathetic members of the media to cover the case. Just as importantly, the family members were willing to answer the same painful questions over and over at news conferences and in TV interviews.


Notably, many of the national media figures who initially devoted time to the shooting are black, which to some is a case study in the need for diversity in newsrooms. The racial and ethnic makeup of newsrooms, where minorities tend to be underrepresented, has long been a source of tension for the news industry.


“On this story, there is a certain degree of understanding that comes from minorities, and particularly African Americans, just because we’ve lived it,” said Don Lemon, the CNN weekend anchor who has covered the case extensively for the past two weekends. He recalled that in a planning meeting for his program, one of his producers, a black mother of two teenage boys, was “almost in tears” as she said, “We’ve gotta do something on this story.”


As the case was catapulted onto the national agenda and calls for Mr. Zimmerman’s arrest increased, prominent black journalists and commentators wrote about it in highly personal terms. “This is the fear that seizes me whenever my boys are out in the world: that a man with a gun and an itchy finger will find them ‘suspicious,’ ” Charles M. Blow of The New York Times wrote on March 17.


A day later, Jonathan Capehart of The Washington Post wrote of the rules he was taught as a teenager: “Don’t run in public,” “Don’t run while carrying anything in your hands,” “Don’t talk back to the police.”


“One of the burdens of being a black male,” he wrote, “is carrying the heavy weight of other people’s suspicions.”


Mr. Zimmerman, a volunteer for a neighborhood watch group, has claimed self-defense and has not been charged with any crime, causing an uproar that was readily apparent on social media Web sites. But for the first 10 days after Mr. Martin’s death, the story was covered solely by the Florida media.


The first national attention appears to have come from CBS News, on March 8, after the network’s Southeast bureau, based in Atlanta, was tipped off to the case. Correspondent Mark Strassmann and producer Chris St. Peter contacted the family’s attorney, Benjamin Crump, and then sent an e-mail story pitch to a group of “CBS This Morning” producers. “We can interview the victims’ parents tomorrow,” they wrote in the e-mail, promising an exclusive. Within 40 minutes, the producers had said yes.


Mr. Strassmann and Mr. St. Peter “knew a story when they saw it, they sniffed it out, and they did all the legwork,” said Chris Licht, the executive producer of the morning show and vice president of programming for CBS News.


That same day, The Huffington Post and TheGrio.com, an arm of NBC News, covered the case. By the end of the week, CNN and its sister channel HLN were also on the case, as were some black radio hosts and bloggers.


National coverage increased somewhat the week of March 12, but really intensified only after March 17, when tapes of 911 calls were released, proving that Mr. Zimmerman was told by a dispatcher that he did not need to follow Mr. Martin. Having the audio — which the local police had previously refused to release — was critical because it gave radio and TV reporters more content for their segments and because it aroused more suspicion about Mr. Zimmerman.


Within days of the national media scrutiny, the United States Justice Department said it would investigate the case, and on March 23 President Obama addressed it directly, furthering the media dialogue.


Some reporters and anchors, like Mr. Lemon and Mr. Blow, said they were urged by their followers on Facebook and Twitter to find out about the shooting — evidence of the effect that the Web can have on news coverage. “People started sending me tweets saying, ‘What are you going to say about this case?’ ” Mr. Blow recalled.


He then looked up local stories about it, contacted Mr. Crump, and arranged for an interview with Mr. Martin’s mother, Sybrina Fulton. “They were very open to talking, and that was very important,” he said.


On television, the family spoke early and often to the Rev. Al Sharpton, the civil rights activist who has radio shows and an MSNBC television show. He was made aware of the shooting by Mr. Crump, who had previously enlisted Mr. Sharpton to speak out against the death of a Florida boy at a boot camp in 2006.


“The attorney called and said, ‘I need you again,’ ” Mr. Sharpton recalled in a telephone interview from Florida, where he staged a rally Thursday night to call for justice. He brought his radio and TV shows with him, thereby amplifying his call.


Mr. Sharpton has used his shows for all manner of advocacy, including support for President Obama and opposition to strict voter-identification laws. He analogized radio, with its hours of airtime and calls from listeners, to “ground forces” and MSNBC as “air strikes” and said, “If you have a war, you’re gonna need both.”


Mr. Crump has publicly thanked the media for paying attention, and so too has the family. Mr. Martin’s father, Tracy, told Gayle King on CBS last Friday, “The world knows Trayvon now.”