Is the punishment for a murder case fare? Are we all getting the same punishment

Is the punishment for a murder case fare? Are we all getting the same punishment that they deserve?  I think they are not due to some of the documentaries I have watch and the stories I have read. Are the judges really looking at the all the evidence and taking their time? I have read two documentaries which are the Murdaugh family and how Alex Murdaugh killed his own son and wife, also got life in person compared to the central park 5, the main point of the central five was about a women being raped by these five man but the five man got wrongly punished because of the lack of police involvement. 
Sources:
https://www.pbs.org/kenburns/the-central-park-five/about
https://www.justice.gov/usao-sc/pr/alex-murdaugh-sentenced-40-years-prison-federal-financial-crimes
https://www.nbcnews.com/news/us-news/alex-murdaugh-face-harsh-sentence-feds-say-failed-polygraph-test-rcna145513
https://www.nbcnews.com/news/crime-courts/alex-murdaugh-indicted-murder-charges-summary-timeline-rcna38026