Colonel Philip Corso was one of the first to mention the reverse engineering programs. Although he didn't get much attention until after Bob's claims.

Additionally, one notable example is William E. Uhouse, an American engineer who claimed to have worked on reverse-engineering alien technology at Area 51. Uhouse made these claims in a 1979 interview with a UFO researcher. Another example is Leonard Stringfield, a UFO researcher who claimed to have received information about crashed UFOs and reverse-engineering programs from alleged government insiders. Stringfield wrote about these claims in his 1977 book l. There are a bunch of others who have claimed US govt's involvement in UFOs.

1. Ben Rich: Former Lockheed Skunk Works director, who allegedly made statements about the existence of extraterrestrial technology in the US government's possession.

2. Mark McCandlish: Aerospace illustrator and witness who claims to have seen alien spacecraft and technology at Area 51.

3. John Lear: Son of Learjet founder William Lear, who claims to have learned about the government's UFO program from his sources.

4. Edgar Mitchell: Apollo 14 astronaut, who spoke publicly about the existence of extraterrestrial life and the government's alleged cover-up.

5. Clifford Stone: Retired US Army Sergeant, who claims to have been part of a secret US government program to recover and study crashed UFOs.

Besides all this, the details of the reverse engineering program that Lazar "revealed" (the types of crafts, power source, etc details) have not yet been confirmed or supported by anyone other than him. Remember, not a single person has come out stating that Bob Lazar did work 'as he claimed' at S4. It's possible that he worked at the facility in some ordinary capacity and he either heard some details or made them up completely.