How did Martin Luther King Jr. get his letter outside of the Birmingham Jail walls?

"Letter from Birmingham Jail" by Martin Luther King, Jr. was taken in bits and pieces from King's confinement in Birmingham prison by his lawyer. It was eventually sent to major national publications, where it received a very wide readership. The letter itself was a response to a letter authored by white clergymen which asked everyone to join together in waiting for the judiciary to decide on issues of racism rather than protesting.
According to The Huffington Post, King's lawyer was named Arthur Shores, and he had a long career of defending people's civil rights before King was ever put in jail in Birmingham. While King was in jail, he wrote the letter on different pieces of paper, like in the margins of newspapers. Shores and other lawyers would take bits and pieces out with them after visiting King and slowly the letter was put together in its entirety outside the prison.
The people who put together the letter worked for the NAACP. Wyatt Walker and Willie Pearl Mackey put the pieces together and then transcribed it for publication. According to the same article, it was difficult for the typist to read the handwriting. King had a chance to look at the complete letter, revise it, and have it taken back out of the prison once it was transcribed.
https://www.huffpost.com/entry/arthur-shores-gentle-giant-of-dynamite-hill-excerpt_n_1837322

https://www.theatlantic.com/magazine/archive/2018/02/letter-from-birmingham-jail/552461/