Updated

A 20-year-old with a weapons cache that included AK-47s was arrested Friday in South Florida on federal charges of threatening to re-enact the Virginia Tech massacre, the U.S. attorney's office said.

Local authorities had arrested Calin Chi Wong at his home last week after finding 13 firearms and more than 5,000 rounds of ammunition, some that could pierce armor, and bullets that could take down aircraft or military machinery.

But the suspect's brother told The Associated Press that Wong "doesn't even know how to use a gun."

Wong bonded out of jail on those charges but was arrested again Friday after the FBI and the Bureau of Alcohol, Tobacco, Firearms and Explosives investigated threats Wong made March 25 on the Internet chat site under the screen name "thehumanabc," according to an affidavit.

Wong told authorities he had made more than 20 threats to people over the Internet in the past year, officials said. He threatened one person, saying that he would be "putting a bomb on him" and that he "wanted to use kamikaze on him," according to the affidavit.

Wong was brought to the federal detention center in Miami, the FBI said. It was not immediately known if he had an attorney.

He is to appear in court Monday, said Alicia Valle, a U.S. attorney's office spokeswoman.

Vincent Wong said his older brother never intended to hurt anyone and stockpiled assault weapons and ammunition at his Homestead home only for investment purposes.

Calin Wong told police he expected the guns, including the AK-47s he owned, would eventually be banned again, inflating prices for the weapons, according to an arrest report.

"He's investing in firearms, meaning buy a lot of firearms. When the ban hits, meaning when Hillary becomes president, she's thinking of banning guns," the suspect's brother said at his family's China King restaurant here, about 30 miles south of Miami. "She bans guns, then guns going to rise up super high."

The brother added: "It's like a hobby. It's like trading Pokemon cards, basically."

Authorities said Wong was angry because he believed he had been ripped off on an Internet gun purchase.

Oregon authorities then learned of a March 25 Internet message allegedly posted by Wong in which he threatened to re-enact the Virginia Tech killings.

Seung-Hui Cho, a mentally disturbed student, killed 32 victims and wounded several others at the school last year before committing suicide.

Homestead police on March 27 searched the home Wong shares with his parents and found the weapons stacked on shelves in plain view, Detective Antonio Aquino said.

Wong was charged with making written threats to kill or do bodily injury via the computer and was released on $7,500 bond.

"He didn't do nothing other than that threatening note, that's it," his brother said. "He doesn't even know how to use a gun."

Additional charges are possible.

"We are tracing all the firearms and we are seeing if any violation of federal firearms laws have taken place," said Carlos Baixauli, a spokesman for the Bureau of Alcohol, Tobacco, Firearms and Explosives.

Wong is not enrolled in college. He graduated from an Oregon high school and attended college for a year before moving in with his parents in Florida, authorities said.