He will serve 50 years, if he survives that long. He has a 75 year sentence, with 25 years only being suspended after 50 years. Virginia convicts can earn good time credits (85% of the sentence), but those credits will not assist this guy in serving less than 50 years.
The Roanoke article mentions that he has been diagnosed on the autism spectrum. This implies that those on the spectrum are prone at times to commit awful crimes, something to which people with autism and their parents would likely disagree - some vehemently. This issue swirled around the Adam Lanza case, and it doesn't seem to have much clarity from a layperson's reading of spectacular crimes involving autism.
If he does have a form of autism, and we only have the record of the psychiatrist and neuroscientist to go on - the mental aspect of a high security prison will be brutal. Not being able to pick up social cues and social context living among violent sociopaths will make life difficult. Not sure that I care - there are consequences to really bad decisions.
This case has an unreal element of cruelty to it. I cannot imagine why a college man and woman would find any kind of connection with a 13 year old girl with disabilities and health problems, and why treating her so cruelly found any form of satisfaction. The running aspect makes it all the more perplexing. Running typically gives one a better sense of self, and not a disconnected one.