It eventually came out that several key witnesses had been pressured into changing their statements.

came 是动词 come 的过去式，come 的基本意思是"来、到达"。 out 是副词，表示"向外、公开"的意思。 came out 是一个短语动词，字面意思是"出来"，在这里引申为"被揭露、被公开"的意思，指真相或信息最终被披露出来。