How to date a recording using background electrical noise

from blog Robert Heaton | Blog, | ↗ original
Three men were accused of selling firearms to South London gangs. At their 2012 trial in Croydon Crown Court, the prosecution played the jury a recording, taken undercover, of the trio allegedly arranging a sale. But the men’s lawyers claimed that the recording was a fake, and that the police had fabricated it by splicing together clips taken at...