Like this man? https://en.wikipedia.org/wiki/Sture_Bergwall
So no, not like that at all.
I submit that allowing such unrepentant and irredeemable evil to exist is more barbaric than a quick death.
For what it's worth, the article you cited states that there was a lack of technical forensic evidence, which was not a problem in the Dahmer case.
As I said before, I can't come up with legal, concrete, and objective measures because I haven't studied law. It's completely unreasonable for you to ask that. Furthermore, as a taxpayer and regular voter, I help fund and choose the people that have said training. It's up to them to figure out how to implement a solution. I can't be expected to do everything.
If we admit that the death penalty is a penalty like any other, then why should it be applied to murderers, who by the way are often poor, deranged or sick people, with troubled or violent upbringing, low IQs and levels of instruction? Why don't apply it to affluent and powerful people who screwed whole nations from the comfort of their offices' chairs, like for example George W. Bush and Colin Powell?
http://mobile.nytimes.com/2007/11/18/us/18deter.html
While there was still people who were challenging the studies the statisticians had moved on because it was considered a settled question.
If you don't agree, how about an opposing viewpoint instead of downvotes?