Knowing only what I have seen here (and knowing that is not the whole story...one way or another) if I had been the judge, I would have granted the stay, not related to anything the French Ambassador had to say.
While I favor the death penalty, I feel that because it can never be undone, there needs to be much care in guaranteeing as fair and through examination of the evidence as possible.
In recent years, I have read reports of several death row inmates who have been proven innocent by use of modern DNA testing. I have also see two cases where a man convicted of rape and having served many years in prison has been exonerated by DNA evidence.
Again, with what I know of this case, the guy looks very guilty, however, I don't think it is outside of our society's responsibility in using the death penalty to perform this DNA test.
If it is possible to use DNA testing on the available evidence, it should be done.
This DNA test is not required to prove the guilt of this man. If it is inconclusive, he burns.
But if it is able to prove, without doubt, that he could not have committed the murders, he walks.
We have enough time to perform these tests.