Luigi Mangione's Full Manifesto Revealed

Luigi Mangione, the suspected shooter in the murder case of UnitedHealthcare CEO Brian Thompson, was frustrated with the "corporation and greed" of the healthcare industry ... this according to his handwritten manifesto.

Journalist Ken Klippenstein recently released the manifesto reportedly found on Mangione when he was detained Monday in Altoona, PA. Law enforcement sources have confirmed the text to TMZ.

The document, a 262-word letter addressed to "the Feds," comments on a number of topics ... including his issues with the healthcare business, especially UnitedHealthcare.

Specifically, Mangione calls out the U.S. for having the "most expensive healthcare system in the world," but being only No. 42 in "life expectancy." LM goes on to call out UnitedHealthcare in particular ... labeling it the "largest company in the US by market cap, behind only Apple, Google, Walmart."

He adds ... "They continue to abuse our country for immense profit because the American public has allowed them to get away with it."

While Mangione apologizes "for any strife" he might've caused, he seemingly hints at the shooting of Thompson, writing, "These parasites simply had it coming."

However, he did not name the UnitedHealthcare CEO directly.

He did tell the feds he respected "what you do for the country," going on to confirm he worked alone ... highlighting "straggling notes and To Do list that illuminate the gist of it."

Mangione ends his note saying this is "not an issue of awareness at this point, but clearly power games at play" -- but he says he's simply "the first to face it with such brutal honesty."