He did.
Washington Post:
Trump swam in mob-infested waters in early years as an NYC developer
https://www.washingtonpost.com/investigations/trump-swam-in-mob-infested-waters-in-early-years-as-an-nyc-developer/2015/10/16/3c75b918-60a3-11e5-b38e-06883aacba64_story.html
CNN:
Donald Trump and the mob
www.cnn.com/2015/07/31/politics/trump-mob-mafia