Can someone explain these charges in the Floyd incident to me

[Totem Polar]

Former Minneapolis police officer Derek Chauvin, who was seen in video footage with his knee on George Floyd's neck, face one count of third-degree murder, one count of second-degree murder and one count of second-degree manslaughter.

So far as I know, there’s only one guy who’s dead over all this. But I’m a legal simpleton.

Source:
https://kstp.com/news/state-files-mo...-2020/5824777/

The real headline, of course, is the request for a co-joined trial:

https://www.startribune.com/prosecut...ing/572092042/

That said, wouldn’t a murder be either 2, 3 or manslaughter, not all at once?

[OfficeCat]

I can't say for certain without seeing the charging documents, but my guess is these are alternative charges - he could be found guilty of any one of them but not all three. The jury would get to pick which is applicable based on the evidence presented. I've seen cases filed that way in my state.