(CNN) -- Shezanne Cassim, an American who was jailed in the United Arab Emirates after posting a video that parodied Dubai teens, returned to the United States on Thursday and sharply criticized the authorities who imprisoned him.
"I did nothing wrong," Cassim said in Minneapolis. "There was nothing illegal about the video, even under UAE law. I was tried in a textbook kangaroo court, and I was convicted without any evidence."
For months, Cassim said, he and others apprehended in the case didn't know why they were behind bars.
"We had no idea of what our crime was. We had no idea how long we'd be in prison for. We weren't actually told what our crime was until five months later, after we were taken in," he said. "Even then, we heard rumors of the charges, and they kept on changing."
In December, Cassim was sentenced to a year in prison and a fine of about $2,700. The charges were not read in court, but the country's main English-language newspaper reported that Cassim was accused of defaming the UAE's image abroad.
UAE officials would say only that Cassim "was charged under the UAE's penal code" and was "entitled to the fair trial protections contained in the UAE's constitution."
Cassim said the reason behind his detention was clear.
"Due to the political situation there, they're scared of democracy. They wanted to send a message to the UAE public, saying, 'Look what we'll do to people who do just a silly YouTube video, so imagine if you do something that's actually critical of the government.' It's a warning message, and we're scapegoats," he said.
U.S. State Department spokeswoman Jen Psaki said Tuesday that after getting credit against his one-year sentence for time served and "for good behavior," Cassim was moved to a deportation facility for processing.
According to his family, Cassim, of Woodbury, Minnesota, ended up serving nine months in prison -- more than half of those before being charged -- before his recent move to a deportation facility.
He had moved to Dubai in 2006, after graduating from college, to work for PricewaterhouseCoopers.
His family says the 29-year-old was arrested in April after uploading a 19-minute video that pokes fun at a clique of Dubai teens influenced by hip-hop culture.
In the 1990s, the label "Satwa G" was given to a group of suburban teens who were known to talk tougher than they really were.
Cassim's video depicts a "combat school" in the Dubai district of Satwa, where these "gangsters" are trained. The training includes how to throw sandals at targets, use clothing accessories as whips and call on the phone for backup.
Shervon Cassim said his brother made the video "just for fun."