Because afaik they charged him with false id, and the evidence looks really bad against him so it was sensible to not go through trial, take such a long time and then be convicted.

And on the murder charges his case is also not great. He wrote a manifesto, we saw camera footage of the shooting and him driving away, there’s apparently evidence that he booked himself into a hotel in that city for exactly that time range, plus because of the public nature and the politicization of the care the state would likely pour a gigantic amount of money into his prosecution and there’s nothing he can do about that.

And also just because doing a plea probably genuinely makes his sentence less severe. But that’s a tactical decision and the exact mechanics will be known, because that’s something he only discusses with his lawyers, which is a good thing.