Fraudster Sarah Panitzke was arrested while walking her dogs in Santa Barbara, Tarragona, on February 27.
She is registered as the UK’s most wanted woman – arrested in Spain after almost a decade on the run.
Panitzke, 47, disappeared in May 2013, while on trial over her part in laundering cash from a £1bn mobile phone tax scam.
The National Crime Agency (NCA) revealed Panitzke’s arrest, who was convicted and sentenced in her absence to eight years in jail.
Simon York, from HM Revenue and Customs, said: “Panitzke had played a pivotal role in the scam, moving millions through offshore bank accounts.
“She had been the subject of a number of most wanted appeals to find fugitives since she vanished.”
The Spanish Guardia Civil said: “Panitzke was tracked down to a town near Barcelona in 2015, but she became aware of the police operation to arrest her, so disguised herself and managed to flee.
“Last month, she was traced to the small town of Santa Barbara and put under surveillance, until her arrest.”
Extradition proceedings have started to take Panitzke back to the UK, the NCA said.
The agency’s international deputy director Tom Dowdall said: “Sarah Panitzke has been on the run for almost nine years. Given the length of time, she might have thought we had stopped searching, but she remained on our radar.
“Joint working between UK law enforcement and our partners in Spain led to her being apprehended, and we will now seek her extradition back to the UK, to serve her prison sentence.
“This should serve as a warning to others on our most wanted list. We will not rest until you are captured, no matter how long it takes.”
