FBI Deputy Director Dan Bongino said Monday that investigators are probing whether Charlie Kirks alleged assassin acted alone or as part of a broader plot, while also revealing troubling signs that the suspect had been "taken over" by ideology leading up to the shooting.Bongino told Fox News' "Americas Newsroom" that although one suspect is in custody, the Bureau is "looking into" possible accomplices."If this was a larger effort, if there was any aiding and abetting, whether it be financial or someone who knew the specifics of it and failed to report that, were looking into that," he told Bill Hemmer Monday. "Theres not going to be a stone left unturned."KASH PATEL'S FALSE START ON CHARLIE KIRK KILLER DRAWS SCRUTINY, BUT FBI NABBED SUSPECT IN THE ENDInvestigators are scrutinizing video showing the gunman leaping from a rooftop after the fatal shot. Bongino said the video was critical in helping the agency crack the case."When youre watching the video, it appears that the gun is either in the backpack or on him," he said. "This is where we got a significant portion of the forensic evidence, which was the key piece of information that cracked this thing open."COMPLETE COVERAGE OF CHARLIE KIRKWATCH THE FULL INTERVIEW:The deputy director confirmed reports that the suspect had voiced violent intentions before the attack."You see this a lot in targeted violence cases, assassinations, school shootings, where the individual expresses in advance his desire to do these specific things. That appears to be the case here as well," he said.ENGRAVINGS ON SHOOTER'S AMMO EXPOSES CHARLIE KIRK ASSASSINATION MOTIVEFamily and coworkers, Bongino revealed, told investigators the suspect had grown more political and withdrawn in the time leading up to the Sept. 10 assassination of 31-year-old Kirk."It appears from the data weve accumulated that this ideology had infected him and had taken over," Bongino said. "He was intent on making Charlie his target and people may have known in advance."TIMELINE OF CHARLIE KIRK ASSASSINATIONWhile stressing that the case is still developing, Bongino said the motive is clear: "Its fairly obvious this was an ideologically motivated attack.""Charlie Kirk is a conservative commentator who sadly and tragically gave his life underneath a sign asking people to challenge his ideas, the very essence of our constitutional republic," he said.Bongino, who described Kirk as a close personal friend, added that the FBIs rapid response should reassure the public."We got our guy in 33 hours. Next time, when theres a crisis, well look at what we can do well and what we can do better," he said. "We can do better than that."