Donte Jamar Sims, accused of threatening to kill President Barack Obama during last week’s Democratic National Convention, will remain locked up while awaiting trial.

U.S. Magistrate Judge David Cayer on Tuesday found probable cause that Sims had committed the crime and ordered him detained in jail until he’s put on trial.

In his detention order, Cayer wrote there is a serous risk that Sims will endanger the safety of another person or the community. “He has failed to appear in state court four times,” the judge wrote. “He has a history of substance abuse and has been unemployed for two years.”

Sims’ attorney told the Observer he would appeal Cayer’s rulings.

Sims, 21, was arrested last week after the U.S. Secret Service found five threatening statements on Twitter from the user name “@DestroyLeague_D.” Records obtained from Twitter through a search warrant showed the account is registered to Sims, according to court documents.

“Well Ima Assassinate president Obama this evening!...Gotta get this monkey off my chest while he’s in town,” one of the tweets said.

Another tweet warned: “The Secret Service is gonna be defenseless once I aim the Assault Rifle at Barack’s Forehead...F* the #DNC!”

A few minutes later, another tweet was sent. “Plotting president Obama’s Murder,” it said.

Threatening to kill the president of the United States is punishable by up to five years in prison and a $250,000 fine.

During Tuesday’s hearing, defense attorney Kevin Tate told the judge that Sims’ tweets weren’t true threats to the president. He pointed out that Sims didn’t have a car or a gun.

Tate urged the judge to let Sims out of jail, arguing that his client is not a threat to the community or a flight risk.

“This was just a young kid apparently high on marijuana seeking attention,” the defense attorney told the judge. “There’s no evidence this was a credible threat. This is a kid who was just using Twitter for attention.”

But Assistant U.S. Attorney Mark Odulio urged the judge to keep Sims locked up in jail.

Odulio introduced an exchange of tweets between Sims and a Twitter user named Lord$ Never Worry who had read at least one of the threats to the president.

“You better stop Tweeting that before the FEDs come looking for you. lol,” Lord$ Never Worry wrote.

“Oh Im ready,” Sims replied.

“You serious??” Lord$ Never Worry asked.

“As a Heart Attack,” Sims replied.

The prosecutor also introduced other tweets Sims had written. One of them, sent in August, said, “Mannnnnnn somebody need to step up and Assassinate Obama...it’s well overdue.”

Odulio called Sims’ tweets serious threats. “The defendant was deadly serious about the threats he was making,” the prosecutor told the judge.

The threatening tweets Sims has been charged with writing were sent on Sept. 3, according to authorities. The next day, a U.S. Secret Service protective intelligence research specialist found them.

Secret Service Special Agent Wayne Bourg went to Sims’ home in Charlotte to question him. Sims admitted using his Twitter account from his home to publish the threats, and “smiled as I read the statements aloud to him,” Bourg wrote in an affidavit.

“Sims stated that he published the statements because he hated President Obama,” the agent wrote. “Sims asserted that he was high on marijuana when he made the threats but that he understood what he was doing and that it was wrong.”

Sims, while being questioned later at the police department, said he was sorry that he had sent the messages threatening to kill the president and wrote an apology, Bourg wrote in the affidavit.

Sims’ grandfather, Louis Sims, told the Observer as he left the courthouse after Tuesday’s hearing that he didn’t think his grandson would have carried out the threats. His grandson, he said, was just fooling around.

“He would never harm the president,” Louis Sims said. “He’d never harm nobody.”