Earlier in the briefing, Gray said investigators had spoken to Robinson’s mother, who said her son had, over the last year “become more political and had started to lean more to the left, becoming more pro-gay and trans rights-oriented”.

He disclosed that the exchange with the roommate then began to explore a motive.

“Roommate: ‘Why?’ Robinson: ‘Why did I do it?’ Roommate: ‘Yeah."’ Robinson: ‘I had enough of his hatred. Some hate can’t be negotiated out. If I am able to grab my rifle unseen, I will have left no evidence. Going to attempt to retrieve it again, hopefully they have moved on. I haven’t seen anything about them finding it,’” Gray said.

I think the motivation is pretty clear at this point. Not sure how this post got 1k+ likes and no one seem to give credible source.

Source: https://www.theguardian.com/us-news/2025/sep/16/charlie-kirk-shooting-prosecutor-utah