He doesn't have to be a suspect in Alexis' case to be compared in a database. JM's DNA was in a database on the Fairfax victim (even though we didn't know it was JM at the time it went in, it was still there). Ergo, his DNA is in whatever database that case is in. The DNA from the Morgan Harrington case matched the Fairfax case. Ergo, JM's DNA (unknown to be JM's at that time) for the Morgan Harrington case was run against whatever database the Fairfax case was in.
Fairfax is in Virginia.
Roanoke is in Virginia. (Morgan)
Shipman, Lovingston, Charlottesvill and Lynchburg are all in Virginia(all of those are associated with Alexis' case).
If LE ran the unknown DNA in Alexis' case against the Virginia state database, and JM's DNA (from the Fairfax case) was in the state, and IF the unknown DNA in Alexis' case was JM, there would be a match of DNA between cases. Whether or not JM was a suspect in Alexis's case.
However, if LE ran the unknown DNA in Alexis' case against the Federal database, and JM's DNA (from the Fairfax and Morgan's case) was ONLY in the state database, and IF the unknown DNA in Alexis' case was JM, there would NOT be a match. Worse yet if LE did not run that unknown DNA against any database.
Point being, JM's DNA was in SOME database somewhere because it eventually matched up to the Fairfax case and Morgan Harrington's case, which had already been matched up before anyone heard of JM. So Laura French's tweet made absolutely no sense at all. And if LE on the Alexis Murphy case had run the unknown DNA found in her case against all databases available to them, they'd be able to say, "Nope, there was no match." the second they were asked to check the unknown DNA against JM. But they don't seem to be able to do so, which would indicate they decided RAT was their man in Alexis' case, and stopped there.
Understand, I think RAT did do it. But this opens a whole can of worms regarding appeals.