MIAMI -

A South Florida man has been arrested, accused of posting threats on Facebook that he would kill President Barack Obama during his University of Miami visit.

In court documents, a U.S. Secret Service agent wrote that Coral Gables police alerted the agency to information that Joaquin Amador Serrapio Jr., 20, of Miami, had posted threats on Facebook.

READ: Complaint affidavit

The agent said that investigators looked at a Facebook account Serrapio kept under an alias and found a post from Feb. 21 that said, "Who wants to help me assassinate Obummer while hes at UM this week?"

Investigators said a post from Thursday, the day of Obama's visit to South Florida, said, "If anyones going to UM to see obama today, get ur phones out and record. Cause at any moment im gonna put a bullet through his head and u don't wanna miss that! Youtube!"

Secret Service agents went to Serrapio's home, where they found an iPad showing one of the threatening Facebook posts as well as two Airsoft pellet guns, according to court documents.

Serrapio was arrested. The Secret Service said he admitted to writing the two Facebook posts.

According to court documents, when agents searched Serrapio's cellphone, they found more threatening messages in an exchange with someone identified as N.M.

"I know i can b killed by this communist administration and im challenging them. Lets see what those (expletive) got," Serrapio wrote, according to the documents.

"Hell yeah im a Boss an the secret service will find that out soon," he wrote in another message.

"Will they see it?" N.M. replied.

"I hope :) i wanna kill at least two of them when they get here," Serrapio wrote, according to the documents.

Serrapio was released from jail on $70,000 bond. He pleaded not guilty, and his next court appearance is set for March 9.