"Mr. Chmieliauskas continued to communicate with Mr. Wylie's team in 2014, as the Cambridge employees were locked in protracted negotiations with a researcher at Cambridge University, Michal Kosinski, to obtain Facebook data through an app Mr. Kosinski had built. The data was crucial to efficiently scale up Cambridge's psychometrics products so they could be used in elections and for corporate clients.

"'I had left field idea,' Mr. Chmieliauskas wrote in May 2014. 'What about replicating the work of the cambridge prof as a mobile app that connects to facebook?' Reproducing the app, Mr. Chmieliauskas wrote, 'could be a valuable leverage negotiating with the guy.'"