The FBI’s no. 2 man said Monday that he suspects Charlie Kirk’s alleged killer Tyler Robinson could have been “aided and abetted’’ by an “extended network’’ — alluding to “multiple warning signs” he gave leading up to the assassination.

As The Post reported Sunday, law enforcement was already probing whether pro-trans online groups, sexualized animal-obsessed “furries” and others connected with Robinson had advance knowledge of his alleged murderous plans.

The groups include communities on the online gaming platform Steam, as well as Armed Queers SLC, which took down its Instagram page after Kirk was murdered.

But now, FBI Deputy Director Dan Bongino suggested that the feds are casting an even wider net — scrutinizing whether anyone in the crowd, including possibly the TikTokker who was asking Kirk a question at the moment of his murder, knew anything about the plot.

Bongino told Fox News’ “America’s Newsroom” host Bill Hemmer that his G-men are “looking into” whether the shocking killing of Kirk — a 31-year-old conservative icon, married dad of two and the founder of Turning Point USA — was “part of a larger effort” and could have involved people providing even financial help, or “someone who knew the specifics of it and failed to report that.”

“We’ll also be dropping a lot of paper, a lot of subpoenas out there, to take a look to see if there was any extended network,” Bongino said.

Kirk was killed by a single bullet to the neck during an event at Utah Valley University on Wednesday afternoon. Robinson — whose live-in boyfriend is trans — was arrested 33 hours later.

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Bongino, asked whether there was any possible connection between the timing of the gunman pulling the trigger and Kirk answering an audience member’s question about mass shootings committed by trans people, said, “We’re investigating that.

“I don’t want to say conclusively right now if there was a connection or not,” Bongino said. “It’s not terribly uncommon for [Kirk] to get questions like that. However, we are looking into that.”

Hemmer asked Bongino about a conversation between Robinson and an unidentified relative at a recent family gathering in which they discussed their mutual distaste for Kirk.

“There appear to have been multiple warning signs” about Robinson going off the deep end, Bongino said. “You just laid out some of them. There were people in his network, friends and family who had stated that he had become more political.”

But questions still remain about how and when Robinson was radicalized. Inscriptions found on the unspent shell casings in the gun used to kill Kirk indicated its owner had an affiliation with pro-trans and anti-fascist ideologies.

A relative of Robinson’s roommate, who is cooperating with authorities and has not been accused of any crime, said they suspect Robinson’s radical politics may have been influenced by their relationship.

“I think Tyler got a whole lot worse in the year they have been dating. They are big gamers, and obviously they have that group that influences them as well as others. But my gut tells me [the roommate] did more of the influencing,” the relative told Fox Digital.

Utah Gov. Spencer Cox said Friday that Robinson had been “deeply indoctrinated with leftist ideology,” despite not being registered with any political party. Robinson “didn’t like” Kirk or his “viewpoints,” authorities have said.

The Post reported Robinson has a live-in boyfriend who is in the process of transitioning from male to female, though it has not been confirmed whether the accused shooter’s level of political involvement changed as a result of that relationship.

Officials have so far been tight-lipped about divulging what exactly put Robinson over the edge on Kirk, but Bongino described the suspect as having “some obsession” with him based on his “digital footprints” — calling the assassination “an ideologically motivated attack.”

FBI Director Patel told Fox on Monday that Robinson “had a text message exchange with another individual in which he claimed that he had an opportunity to take out Charlie Kirk — and he was going to do it because of his hatred for what Charlie stood for.”

The same threatening sentiment was allegedly found in a handwritten note, which Patel said was “destroyed” but that the bureau still has “evidence to show what was in that note.” The director said it included Robinson “saying, ‘I have the opportunity to take out Charlie Kirk, and I’m going to take it.’ “

The FBI declined to comment further when asked by The Post for clarification about the handwritten note or its contents.