TL;DR: It is Ed Wescott. Read on for how I reached this conclusion.

In Joe Rogan Experience Episode 1299, Annie Jacobsen, an American investigative journalist, author (and 2016 Pulitzer Prize finalist in history), mentions at 9:05 (Youtube timestamp) that her Source with a Q Clearance, was and I paraphrase:

A major player in the Manhattan Project. He went on and worked in the atomic energy commission. There’s a wing of a museum named after him. His accolades his awards were so extraordinary. He recently died, and gave me permission to write about him after his death.

The Source told her that the Roswell incident was Stalin sending surgically modified children in experimental Nazi hovering discs into American territory to create a War of the Worlds type panic inside USA. Stalin did it also to demonstrate that USSR was ahead of USA in aerospace technologies, although USSR did not have the Atom Bomb, while having better Black Propaganda capabilities.

The Source also confessed that US Government (i.e. DOE a.k.a Atomic Energy Commission a.k.a NNSS) also had done surgical/genetic experimentation on mentally challenged children to see if they can replicate what Stalin did.

Annie Jacobsen does not reveal the name of her Source, and saves it for her next book (maybe). But given the information above I was able to mine WikiData and come up with an answer. Here is how I did it:

First I wrote a SPARQL Query for Wikidata Query Service (WDQS)

SELECT ?person ?personLabel ?death WHERE { ?person wdt:P1344 wd:Q127050. ?person wdt:P570 ?death SERVICE wikibase:label { bd:serviceParam wikibase:language "[AUTO_LANGUAGE],en". } } ORDER BY DESC(?death)

What it does is it finds people involved in the Manhattan project and sorts them by how recently they died (because Annie said the Source died recently). The result set is quite large but I limited the number of results below:

person personLabel death http://www.wikidata.org/entity/Q376617 Geoffrey Chew 2019-04-11T00:00:00Z http://www.wikidata.org/entity/Q666681 Ed Westcott 2019-03-29T00:00:00Z http://www.wikidata.org/entity/Q64188 Roy J. Glauber 2018-12-26T00:00:00Z

Now all I needed to find was someone in the above list who worked for the Atomic Energy Comission. Ed Wescott’s Wikipedia page says he worked for the Atomic Energy Comission. There is also an museum which opened in 1949 about the Manhattan Project, now called the American Museum for Science and Energy which is very fond of Ed Wescott. Ed Westcott’s wikipedia page also talks about museum sections dedicated to his work:

So I conclude that Ed Wescott was person who knew about American experiments on mutating/mutilating mentally challenged childen.

I hope my blog will not get taken down for exposing the identity of a person with an Above Top Secret, Q Clearance who knew about the crimes that USA/DOE/AEC did by experimenting on children. I will take a backup of the blog just in case, after I publish this post. Please don’t dox me. I am just a loser on the Internet. Please don’t drone me either. I hope I am just being paranoid.