How can they possibly find him anything other than guilty of murder? Having listened to the summing up, even if you put aside the problems it would cause on the streets if he was found not guilty, the evidence was so compelling that he must surely be found guilty.
I cannot find the link now but what I read was that the prosecution sums up, followed by the defence, but the prosecution can then challenge the defence. I may have got this wrong; if so I apologise.
"In second-degree murder, the act that led to someone's death could have been intentional or unintentional. The maximum sentence is 40 years in prison.
Third-degree murder means an individual has acted in a way that endangered one or more people, ending in death. This charge was added later and experts say it is easier to prove in court, but the jail sentence would be lower."
That's the difference between US and UK law. In the UK there are no degrees of murder and intent must be proved. The US system seems to make manslaughter almost redundant.