I found the following posts by the VI:
July 26, 2017:
“As far as I know, no luminol was used in the shop. The blood drops were tested and are confirmed to be Papaw's blood.”
TX - TX - Michael Chambers, 70, Hunt County, 10 March 2017 #2
July 27, 2017:
“Luminol has not been used at all, as far as I know.
[RSBM for focus]”
TX - TX - Michael Chambers, 70, Hunt County, 10 March 2017 #2
July 27, 2017:
[Replying to a previous post: “If they didn't spray luminol, how do they know there was no blood or skin on the vehicles or anything else except the dowel and the drops on the floor? They strictly went by eyesight alone? Ugh. Sorry, but they suck. I hope it's not too late for your PI to do it.”]
“I believe they went by eyesight alone, yes. I will be asking my family to request that the PI use Luminol in the shop, house and vehicles. Anyone know how late is too late for that sort of thing?”
[Just to avoid confusion: The PI being reference above is not Klein.]
TX - TX - Michael Chambers, 70, Hunt County, 10 March 2017 #2
Aug. 31, 2017:
“[RSBM for focus]
Luminol was used in the workshop and portions of the home and did not yield anything suspicious.
[RSBM for focus]”
TX - TX - Michael Chambers, 70, Hunt County, 10 March 2017 #3
So I think both of you are right: Luminol was not used by HCSO, but it was by the first PI, at least according to the VI.
Personally, I do think that Klein has likely used it, IMO.