FORT LAUDERDALE—FBI Agent Daniel Alfin gained international attention when he led a team that shutdown a major worldwide child pornography website. Agent Laura Schwartzenberger worked more anonymously, teaching children and adults how to avoid online sexual exploitation. Alfin and Schwartzenberger, gunned down on Tuesday while serving a search warrant at a child pornography suspect’s South Florida apartment, devoted their careers to capturing criminals who sexually abuse youngsters, often times testing the legal boundaries of computer privacy. “We are still reeling from the news,” said Shelley Allwang, director of the Exploited Children Division at National Center for Missing & Exploited Children. “I feel lucky to have worked with people who had such commitment and resolve.” The suspect was identified Wednesday as 55-year-old David Huber, who lived at the apartment complex. A law enforcement official familiar with the matter said investigators are looking into whether Huber may have been using a camera …