Police in Florida initially sought an arrest warrant for the neighbourhood watch guard who shot and killed unarmed black teen Trayvon Martin, but were overruled by prosecutors, according to media reports.
The Miami Herald said police in Sanford, Florida applied for the arrest warrant in the early stages of the investigation, contrary to suggestions that there had been inadequate probable cause for a prosecution.
The daily cited a police incident report that described the shooting of the 17-year-old by neighbourhood watch captain George Zimmerman as "homicide/negligent manslaughter."
Prosecutors however, held off approving the warrant, pending further review, according to the Herald and other media reports.
Mr Martin, a high school student, was fatally shot on February 26 by Mr Zimmerman, a white Hispanic who said he acted in self-defense.
A surveillance video meanwhile released late Wednesday by ABC News showed Zimmerman handcuffed at a police station after the shooting, but showing no apparent signs of serious injury.
Mr Zimmerman had said Mr Martin punched him in the nose, knocked him down and slammed his head into the ground before he had pulled the trigger of his gun.
The case has unleashed a national uproar and reopened old wounds over race relations in the United States.
A controversial Florida law allows the use of deadly force when a person has a reasonable fear of death or serious injury - which Mr Zimmerman, through surrogates interviewed in the media, has said was the case when he shot Trayvon.
Since the teen's death, there have been numerous large public protests calling for Mr Zimmerman's arrest, but the 28-year-old has not been detained, prompting outrage from rights groups which describe the shooting as a case of racial profiling and decry what they allege are racial inequalities in the US criminal justice system.
Special prosecutor Angela Corey told the Miami Herald that police filed a "capias request" to the state attorney, a recommendation that criminal charges be made.
"But obviously something gave investigators pause," an anonymous source in the state attorney's office told the newspaper.
"We get capias warrants all the time. That doesn't mean we file charges right away. We investigate to see if it's appropriate," the source added.
Chris Serino, the lead detective on the case, meanwhile told ABC News on Tuesday that he filed an affidavit on the night of the shooting stating that he was unconvinced about Zimmerman's version of events.
Serino separately told MSNBC that he was not at liberty to discuss the case, but felt encouraged by the new investigation into the shooting, and he was "looking forward to the truth coming out."
Mr Martin's mother, however, told CNN that she thought authorities were properly probing the circumstances of the shooting.
"I feel confident that they are going to do a thorough investigation," Sybrina Fulton told the US broadcaster.
"We're trying to be patient, even though it's been over a month. We're still trying to be patient and still trying to press on for justice."