Herzog was implicated in doping practices as part of investigations connected with Operación Galgo. Her coach at the time, Manuel Pascua Piqueras, was a central figure in the scandal. After being interrogated by the police, she was ultimately not charged of an offence after the evidence against her was destroyed.[3] In 2013, Dutch magazine Vrij Nederland published a series of email excerpts which it claimed demonstrated Herzog obtaining performance-enhancing drugs during 2011 and 2012. Following this, her new coach Brad Hudson decided to cease working with Herzog, despite her claims that the magazine's assertions were untrue and no formal proceedings were brought against her.[4] Herzog received a two-year doping ban after she gave a positive test in March 2014. She claimed that the positive test was a mistake and that she had never used banned substances.[5]