The made so much noise doing it the Prisoners complained and they had to erase the audio from the video of the surveillance tape.
http://www.borderlandbeat.com/2015/08/cnn-reports-that-journalist-obtained.html#more
The government allegedly had information as far back as March that Guzman’s people were looking for blueprints of the prison, Hernandez said the documents show. Prisoners told investigators that they complained to prison officials about “excessive noise” that sounded like construction two weeks before the escape, Hernandez said.
And a clip of surveillance video released by the government to show the moment Guzman walked into the shower in his cell and never reappeared isn’t the full story, the investigative report said.
According to the documents, the surveillance video had audio where the banging of metal against concrete can be heard, Hernandez said.
“Instead of doing something about it and prevent the escape, the government just let him go,” Hernandez said.