The problem with that is because they lived together, any such DNA could come from incidental contamination. Plus, any such evidence would have been collected up to a decade ago, and they would have had plenty of time to analyze it if they had it. They almost certainly already had samples of SA's DNA prior to that since it would have been collected incidentally during their initial investigations. If it was not sufficient then, why would be be sufficient now? Because of that, any DNA evidence would be of limited use other than to show they were physically associated with each other, but we already know that since they lived in the same house.
The arrest, according to news reports, appeared to be due to the current DA reexamining the evidence as a cold case, and was based primarily on recent interviews. So, I doubt there is anything actually new, other than perhaps certain people changing their account of events from a decade ago.
New details have been released on the arrest of Shawn Adkins in connection with Hailey Dunn’s murder.
www.cbs7.com
The sequence of events apparently was:
1) The DA looking at the cold case in 2020 and talking to the Texas Rangers (TR)
2) The TR reexamining the evidence and talking to several people
3) The TR identifying SA as a suspect
4) The TR getting a warrant to collect a sample of SA's DNA
5) The TR getting a warrant for arrest a few days later
I think there is a pretty good chance that the DNA is irrelevant, and that it was just collected so it could be on hand if needed. If that is the case then the arrest would be based on these additional interviews they carried out.
We can likely rule sexual assault out. If the DNA evidence was in the form of semen for example, then SA would probably have been charged with sexual assault as well, but he has been charged with homicide and disposal of a body only. Plus, they would have definitely looked for that sort of thing when they found the remains, not only now, and apparently did not find anything of that nature, otherwise they definitely would have got a search warrant to collect his DNA at the time since he was a publicly announced person of interest.