The story goes that Oppenheimer poisoned an apple on Blackett’s desk, then left. Blackett never ate the apple, but Oppenheimer’s friends reported the incident, and Cambridge University did find out.
The school’s administrators wanted to press charges for attempted murder, but Oppenheimer’s wealthy father stepped in and managed to talk them out of it. Oppenheimer simply got off with probation.
Source: https://www.buzzfeed.com/crystalro/oppenheimer-atomic-bomb-manhattan-project-facts