Federal authorities arrested a former school teacher and his twin brother on Thursday in New York City after finding explosive materials in the brothers' Bronx apartment.
Police said they had been monitoring Christian Toro and his brother Tyler in recent months following a Dec. 4 bomb threat at Harlem Prep, the school where Christian worked at the time.
"Neither of these two individuals were on our radar before this, nor did they have any criminal background," John Miller, New York's counterterrorism deputy commissioner, said during a news conference.
What's the story?
In December, police arrested a female student, who was having a sexual relationship with Christian, in connection with the bomb threat, and Christian resigned as a teacher shortly after, the New York Post reported.
After Christian quit his job, his brother Tyler returned Christian's school-issued laptop to the charter school.
School officials searched the computer and found bomb-making information, which they turned over to law enforcement.
Investigators questioned Christian on Feb. 8, but he maintained he was innocent.
They also spoke to students at Harlem Prep.
Investigators allege that Christian paid at least two students about $50 an hour to come to the brothers' apartment to “break apart fireworks and store the powder that came out of the fireworks in containers,” according to the complaint.
On Thursday, agents searched the apartment and found a host of materials used to make explosives including iron oxide, aluminum powder, potassium nitrate, and a glass jar containing explosive powder, the FBI said in a news release.
They also discovered a handwritten diary with Tyler's name.
“We are twin Toros strike us now, we will return with nano thermite" and "I am here 100%, living, buying weapons. Whatever we need,” were among the writings in the diary, according to the FBI.
A backpack that agents believe belonged to Christian held an index card with handwriting that read, “Under the full moon the small ones will know terror.”
It's still unclear what the brothers may have been planning to do, officials said.
Is there an ongoing threat?
“Information from citizens stopped a significant threat to public safety,” FBI New York division Assistant Director Bill Sweeney said. “We have no indication that there is any additional threat from these individuals.”
What are the charges?
Authorities charged Christian with one count of unlawfully manufacturing a destructive device and one count of distribution of explosive materials to a minor.
On Friday, Christian appeared in court where a federal judge denied him bail.
Tyler is charged with one count of unlawfully manufacturing a destructive device. His arraignment has not been scheduled.
The brothers pleaded not guilty to the charges against them.
Police arrested Christian on Jan. 31 for allegedly raping a 15-year-old girl. The girl is the same one who made the bomb threat to Harlem Prep, according to the Post.