As a Yale University historian was going through the national archives researching for a book about FBI Director J. Edgar Hoover she uncovered the unedited "suicide letter" sent to Dr. Martin Luther King Jr. by the FBI.

It was a failed attempt by an FBI deputy posing as a civil rights activists to unsettle King less than two months before he would accept the 1964 Nobel Peace Prize. 

"I was surprised to find a full, uncensored version of the letter tucked away in a reprocessed set of his official and confidential files at the National Archives," Beverly Gage, the Yale professor who found the unredacted letter, told the New York Times.

Hoover desperately feared King and had his agents searching for whatever they could find to take King down. The best they could find was King's extramarital affairs. 

The typewritten note - filled with misspellings and grammatical errors - was written by an agent named William Sullivan. It was accompanied by a cassette tape with evidence of King's affairs, which was recorded by the FBI who wiretaped his hotels and homes, NY Times reported. 

"Listen to yourself you filthy, abnormal animal," the letter reads. "You are on the record. You have been on the record - all your adulterous acts, your sexual orgies extending far into the past. This one is but a tiny sample. You will understand this. Yes, from your various evil playmates on the east coast to [sic] and others on the west coast and outside the country you are on the record. King you are done."

King left for Norway before the letter arrived, making his wife, Coretta, the first to read it. 

The letter ends by giving King 34 days to kill himself.

"There is only one thing left for you to do. You know what it is," the letter concludes.