Federal prosecutors are investigating whether U.S. President Donald Trump's inaugural committee misspent some of the funds it raised, the Wall Street Journal reported on Thursday,citing people it said were familiar with the matter.

citing people为现在分词短语作reported的方式状语。people后为省略了关系代词who的定语从句。（who) it said were familar with the matter.为嵌入式定语从句，who是it said的宾语从句中的主语，可以省略。