The police chief at the center of a growing storm in the United States over the fatal shooting of an unarmed black teenager by a white crime watch volunteer stepped down temporarily Thursday. Sanford Police Chief Bill Lee, who has been criticized after his department failed to arrest self-appointed watch captain George Zimmerman, said he was leaving his post temporarily because he had become a \"distraction. A million people have now signed an online petition calling for justice for 17-year-old Trayvon Martin shot and killed by Zimmerman in a gated Florida community on February 26. Zimmerman says he acted in self-defense, after the teenager instigated a violent confrontation and he has not been arrested or charged with any crime. \"It is my hope that the investigation process will move forward swiftly and appropriately through the justice system and that a final determination in this case is reached,\" Lee told a press conference. \"I do this in the hopes of restoring some semblance of calm to the city, which has been in turmoil for several weeks,\" he added. Local law enforcement officials say they believe Zimmerman cannot be prosecuted thanks to Florida\'s landmark 2005 \"Stand Your Ground\" law, which allows state residents to use lethal force in self-defense. Change.org, the organizers of the online petition drive, who included the dead teen\'s grieving parents, said they have been registering new signatures at the rate of 50,000 per hour. The extent of the public anger in the explosive case and the degree to which it has dominated the national media is surprising even for the United States, where lingering racial wounds regularly become national talking points. In this case, those crying for Zimmerman\'s arrest have noted that he called the police several times while tracking the actions of the teenager, whom he said looked \"real suspicious,\" according to transcripts released by police. Although he was told by dispatchers not to pursue the youngster, Zimmerman apparently followed him anyway, eventually shooting him with his nine millimeter handgun, although the exact circumstances remain unclear. Much of the public resentment has focused on Lee, with local officials late Wednesday passing a \"no confidence\" measure over his handling of the incident. \"I take no pleasure in a public flogging of our police chief,\" said Mark McCarty, a member of the five-member panel who submitted the motion at a packed hearing. \"But he really should turn in his resignation.\" Sanford\'s city manager Norton Bonaparte said his community and the nation were going through a \"very difficult time\" in the wake of the incident. He called for an independent review of police action. \"I ask that the citizens both of Sanford and of the country understand that the judicial process is put in place and what the city of Sanford wants more than anything else for the Trayvon Martin family is justice,\" he said. Bonaparte noted that the state attorney\'s office, the Florida Department of Law Enforcement, the US Justice Department and the FBI were participating in the investigation of the case. Some residents of Sanford, and the larger African American community across the United States, said the case is the latest example of the racial profiling and unjust treatment of blacks by the country\'s criminal justice system. \"I\'m a normal mother,\" said Sybrina Fulton. \"My heart is broken. I keep thinking he is going to walk in through the door and the nightmare is going to end. I just want justice for my son,\" she said. Fulton was a speaker at \"A Million Hoodies March\" held at a New York park, which drew several hundred people wearing the same sort of sweatshirt that her son wore when he was shot. Trayvon\'s father, Tracy Martin, said the family was not \"looking for revenge, we\'re looking for justice -- the same justice anyone would expect if their son were shot and killed for no reason.\" Ben Jealous, president of top civil rights group the National Association for the Advancement of Colored People led a rally in Sanford late Wednesday promising to keep up the pressure. Civil rights advocate Al Sharpton, meanwhile, was planning a protest march late Thursday to apply additional pressure on officials to prosecute Zimmerman.