Martin, 17, was suspended by Miami-Dade County schools because traces of marijuana were found in a plastic baggie in his book bag, family spokesman Ryan Julison said. Martin was serving the suspension when he was shot Feb. 26 by George Zimmerman, who was patrolling the neighborhood that Martin was visiting with his father.
Martin's mother, Sybrina Fulton, and family attorneys blamed police for leaking the information about the marijuana and Zimmerman's claim about the attack to the news media in an effort to demonize the teenager.
"They killed my son and now they're trying to kill his reputation," Fulton told reporters.
The Sanford Police Department insisted there was no authorized release of the new information but acknowledged there may have been a leak. City Manager Norton Bonaparte Jr. said it would be investigated and the person responsible could be fired.
Martin family attorney Benjamin Crump said the link between the youth and marijuana should have no bearing on the probe into his shooting death. State and federal agencies are investigating, with a grand jury set to convene April 10.
"If he and his friends experimented with marijuana, that is completely irrelevant," Crump said. "What does it have to do with killing their son?"
The state Department of Juvenile Justice confirmed Monday that Martin does not have a juvenile offender record. The information came after a public records request by The Associated Press.
Zimmerman, 28, claimed he shot Martin in self-defense and has not been arrested. Because Martin was black and Zimmerman has a white father and Hispanic mother, the case has become a racial flashpoint that has civil rights leaders and others leading a series of protests in Sanford and around the country.
Meanwhile, the Orlando Sentinel reported that Zimmerman told police he lost Martin in the neighborhood he regularly patrolled and was walking back to his vehicle when the youth approached him from behind. The two exchanged words, Zimmerman said, and Martin then punched him in the nose, jumped on top of him and began banging his head on a sidewalk. Zimmerman said he began crying for help; Martin's family thinks it was their son who was crying out. Witness accounts differ and 911 tapes in which the voices are heard are not clear.
The Sanford police statement said the newspaper story was "consistent" with evidence turned over to prosecutors.
Earlier, city officials named a 23-year veteran of the Sanford police department as acting chief. The appointment of Capt. Darren Scott, who is African-American, came days after Chief Bill Lee, who is white, temporarily stepped down as the agency endured withering criticism over its handling of the case.
"I know each one of you - and everyone watching - would like to have a quick, positive resolution to this recent event," Scott told reporters. "However, I must say we have a system in place, a legal system. It may not be perfect but it's the only one we have. I urge everyone to let the system take its course."
The Sanford City Commission held its first meeting Monday since giving Lee a no confidence vote, which led to his ouster. Martin's parents both addressed the panel, urging them to take steps to arrest Zimmerman. More than 500 people crowded into the meeting, which was moved from City Hall to the Sanford Civil Center.
"We are asking for justice," said Tracy Martin, the teenager's father.
Civil rights leader Al Sharpton warned commissioners that Sanford risked becoming a 21st century version of the civil rights struggle in the South during the 1960s.
Sharpton said Martin's parents endured "insults and lies" Monday over reports that their son attacked Zimmerman.
Outside the commission meeting, several thousand people carried signs, rallied and marched in Martin's support. Organizers said some 2 million signatures had been collected on an online petition demanding Zimmerman's arrest.
"It seems like the police did not do the normal things they should have done. But that's going to have to take its own process now," said the Rev. Marilyn Beecher, a Methodist minister who came from Daytona Beach to attend the rally. "It's important that we all stand for justice and that the community leaders know that this is not going to be overlooked."
Martin's family spoke at the rally attended by at least a thousand people.
Tracy Martin called the crowd his "backbone."
"As I see the crowd here, I see Trayvon all over," Tracy Martin said. "I know he is saying to me, 'Dad, I'm proud.'"
Also Monday, an attorney for Martin's mother confirmed that she filed trademark applications for two slogans containing her son's name: "Justice for Trayvon" and "I Am Trayvon." The applications said the trademarks could be used for such things as DVDs and CDs.
The trademark attorney, Kimra Major-Morris, said in an email that Fulton wants to protect intellectual property rights for "projects that will assist other families who experience similar tragedies."
Asked if Fulton had any profit motive, the attorney replied: "None."
Anderson reported from Miami. Associated Press writer Suzette Laboy contributed from Sanford.