Facebook said Friday that in 2015, it discovered that a professor at the University of Cambridge, Aleksandr Kogan, had shared data he collected via a Facebook app from as many as 270,000 users with Cambridge’s parent company, Strategic Communication Laboratories, and a second firm, Eunoia Technologies.

Paul Grewal, Facebook’s vice president and deputy general counsel, wrote in a blog post Friday that Kogan and the companies claimed to have destroyed the data. But executives recently received reports that some of the information was kept. Facebook has now suspended them all pending an investigation.