The alleged "ringleader" of a planned mass casualty event at the UFC Freedom 250 event is an illegal immigrant from Mexico. 

Abraham Alvarez, who federal documents identify as the "ringleader" of the alleged plot, overstayed his visa, according to Fox News, which cited Homeland Security information. 

Alvarez came to the U.S. as a child, and his B2 visa had expired in 2001. He remained in the country, and the Obama Administration granted him deportation relief in 2014 through the Deferred Action for Childhood Arrivals (DACA) program.

Authorities have arrested five suspects in the plot. Prosecutors allege they were planning to launch drones carrying explosives, which would detonate above the crowd. They had planned to use snipers to shoot "high-value targets," steal military ordinance and hide in safehouses after the attack. 

Each plotter faces a maximum penalty of life in prison and a $250,000 fine, if convicted of conspiracy to commit murder. The plot would also carry an additional maximum penalty of five years in prison since it was a plan to carry out violence on White House grounds.