Deleon studied business administration at California State University, San Bernardino, but withdrew in September after first enrolling five years ago, said university spokesman Joe Gutierrez.
Court documents show the men talked about their propensity for violence.
Santana, who claimed he went to Mexico to learn how to shoot different kinds of guns and how to make explosives, wanted to be a sniper. Deleon said he hoped he could be on the front lines or use C-4, an explosive, in an attack.
Gojali, a U.S. citizen, was recruited in late September and he said he would be willing to kill, court documents state.
"I watch videos on the Internet, and I see what they are doing to our brothers and sisters. ... It makes me cry, and it gets like I'm, like, so angered with them," Gojali said.
Gojali's father, Ghazali Musa, said he hadn't heard from his son for three months when he suddenly showed up at the family house last week and said he was leaving on a long trip with a friend.
Gojali's younger sister said the family learned of his arrest through news reports that left them stunned.
"He's not even remotely close to being violent at all," the 18-year-old sister told the Associated Press in an interview in front of the family home. "He's not capable of any of this."
She said Gojali — vulnerable, unemployed and lacking even a high school diploma — had recently become fast friends with Deleon, who was a compelling speaker and popular figure at the mosque the two attended.
"I just think he was lost. I think peer pressure is one of his biggest problems in life, and that's why he's in trouble now," said the sister, who requested anonymity because she did not want to be associated with the alleged crimes. "A lot of people are saying he was brainwashed by this guy, and my brother, not being employed, he offered him rides to places, and to him that was a sign of a true friend."
This past summer, plans to travel to Afghanistan became clearer for the group.
They talked about how they would avoid detection. They talked about opening an Afghan orphanage or possibly posing as cologne salesmen. They finally devised a cover story that they were going to attend Kabir's fictional wedding.
It's unclear whether Kabir actually made contact with Taliban or al-Qaida fighters, but in an August video conversation with Deleon, Kabir was with a shiekh or an imam, the complaint said.
Kabir also had intended to go on a suicide mission earlier this month but got sick, according to the court documents. He indicated he would wait for the group, which included the FBI informant, before staging an attack, according to the affidavit.
Court documents also show the confidential informant had been working with the FBI for more than four years and received more than $250,000 and unspecified immigration benefits. The informant had been previously convicted of trafficking pseudoephedrine.
Before going, Deleon said he was going to leave parents a farewell letter. Asked by the informant if Deleon could lie about his true intentions in the letter, Deleon said, it's OK to lie in war. "I believe right now ... we are in a state of war," he said.
Using the informant's debit card, Deleon bought four tickets for a flight from Mexico City to Istanbul scheduled to leave this past Sunday. Had the men made it to Afghanistan, they would have initially joined the Taliban and then graduate to al-Qaida, Bowdich said.
"They saw this as jihad. They saw this as their way to push out the aggressors," Bowdich said.
Even if he failed in a terrorist training camp, Santana said, he would continue trying.
"If for some weird reason, if I can't handle it, I'm not going to give up," he said, according to court documents. "Like, because, this is my strong intention. This is what I desire of doing in this life."
Associated Press writers Gillian Flaccus, Julie Watson, Raquel Maria Dillon and Shaya Tayefe Mohajer contributed to this report. Watson reported from San Diego.