Is it suspicious that Milton William Cooper wound up dead by gunshot in 2001?

It's suspicious that anyone who writes a book about UFOs passes away that young.

However, there is also a 50% chance that he actually did take his own life.

But, if you look at the track record of everyone who has had a TV interview or spoken on the radio or written books on UFOS it is very expected that they might disappear or die unexpectedly. Especially this was true before 1990 when the Berlin Wall fell. Then for about 10 years time people could publish almost anything until 9-11 happened and things became secretive and people started disappearing unexpectedly around UFOS once again. 

So, Yes, it is very very suspicious that he died a little less than two months after 9-11 when the government started shutting down and making people disappear again after an about 10 year hiatus where things were freer. The new paranoia about Islamic Terrorists made government people very terrified of Islamic Terrorists getting relationships with UFOS like Hitler did during World War II with the Reptilians where (supposedly) they sent U-Boats with Anti-Gravity units supplied by the Reptilians and built a base on the moon. "If you believe what Corey Goode says who is reported to have been to this base with  a secret part of the U.S. government, then this is what happened".

I personally believe that JFK was assassinated partly because he wanted to release the full information on UFOS or now sometimes they are called UAP (Unidentified Aerial Phenomena). I like UFOS better. (Unidentified Flying Objects).