Charlie Kirk's alleged assassin Tyler Robinson wrote a note saying he was going to 'take out' the conservative commentator before he shot him dead, according to FBI director Kash Patel.

'I have the opportunity to take out Charlie Kirk and I'm going to take it,' the note read, Patel said on Monday morning during an appearance on Fox News.

'The note was written before the shooting, it was in the suspect's partner's home,' Patel said.

'We have since learned the note - even though it was destroyed - we have found forensic evidence of the note and we have confirmed what the note said because our aggressive interview posture at the FBI.'