"My belief is if we took this into a courtroom with 12 members of our community on our jury, they would tell me, 'Come on guys, you have more important things to spend your time on,'" District Attorney Steve Wagstaffe said. "And I share that view."
Marman was arrested on suspicion of trespassing, battery of a police officer and obstruction after police say he refused to leave the US Airways flight on the captain's orders.
The incident sparked allegations of racial profiling after a photo surfaced of a man who flew aboard a US Airways flight wearing skimpy women's panties and mid-thigh stockings days before Marman's arrest. That man was white. Marman is African-American.
Dozens of people gathered outside San Francisco City Hall on Tuesday in support of Marman. San Francisco Supervisor Malia Cohen told the crowd that she planned to introduce a resolution asking San Mateo County prosecutors to dismiss the case and for a formal apology from the airline.
"I've been trying to search myself and search whatever information that was given through the media to find out what Deshon had did wrong," Marman's mother, Donna Doyle, said in a phone interview on Wednesday. "And for the life of me, I couldn't find anything."
Police also said Marman injured an officer while being taken into custody. But Wagstaffe said the officer suffered a minor scratch and twisted knee but no significant injuries. Marman should have left the plane at the request of police officers and a sheriff's deputy, Wagstaffe said, but his refusal may have reflected his mental state. Marman had attended a friend's funeral the previous day.
"I think the (district attorney) realized the real villain in this case was US Airways, not Deshon Marman,"Marman's attorney, Joseph O'Sullivan, said.
O'Sullivan and Doyle said Marman was not available to comment.
The incident began when Marman was asked repeatedly to pull up his pants but did not listen, according to airline officials. They have said he was exposing a body part.
O'Sullivan has denied that, and Wagstaffe said Wednesday his investigation found no evidence that a body part was exposed.
Liz Landau, a US Airways spokeswoman, said the airline stands by its employees' claims that Marman's body part was exposed.
The airline is hopeful that the district attorney's decision will allow Marman and his family to "move past this incident," she said.
"As the (district attorney) noted, Mr. Marman could have resolved the situation quickly at the time of the incident had he chosen to do so," she said.
The airline has previously said Marman was thrown off the plane not because of his clothing, but because he refused an employee's request.
Marman plans to file a lawsuit against US Airways alleging he was the victim of racial profiling, O'Sullivan said.