The FBI has launched an investigation into several left-wing groups in Utah to determine whether they had prior knowledge of Charlie Kirk’s assassination, Axios reported.

On Saturday, Fox News said the suspected gunman, Tyler Robinson, had been living with a transgender partner before the attack — a detail later confirmed by multiple outlets.

Public records show 22-year-old Lance Twiggs shared Robinson’s address, and a relative confirmed to the New York Post that “yes, they were roommates.”

According to an Axios report citing six sources familiar with the case, investigators believe the shooter viewed Kirk’s stance on transgender issues as “hateful” toward Twiggs. They see Robinson’s anger over those views as central to establishing a motive in the political assassination that has reverberated worldwide.

A relative, speaking anonymously to the outlet, described Twiggs as the “black sheep” of their St. George, Utah family and said she did not know his political views or whether he was transitioning, though she added it would not surprise her.

One neighbor told reporters he had seen Twiggs and Robinson kissing and holding hands on multiple occasions. Another told The Post that two weeks earlier, several people driving cars with out-of-state plates were observed coming and going from the residence. “They did not give off a good vibe,” the neighbor said.

All six sources familiar with the investigation told Axios that authorities believe Robinson was in a romantic relationship with Twiggs. They added that investigators initially withheld Twiggs’ gender identity from the public because Twiggs was being “extremely cooperative” with authorities.