First degree murder is likely a direct result of LEOs being charged and convicted in the George Floyd death. They are hoping it gets plead down, because they won't get a conviction. However it definitely gets attention.
I'm not saying you should NEVER position someone in a prone position; cops do this all the time, as a means to restrain a violent person. however, once the situation is under control, don't keep in that position. These EMS providers should have known better, as this is a known consequence, especially when the patient is prone with the strap putting pressure on their back.
Civil penalties against them and their employer? I can support that. Criminal charges? yeah, I can support that too, provided the charges are appropriate. First degree murder charges? sorry, that's a bridge too far.