Former Panamanian President Ricardo Martinelli, who has been held in detention on illegal wiretapping charges, was transferred on Monday to a public hospital in Panama City, where he was in stable condition, authorities said.

Carlos Carrillo, one of Martinelli’s lawyers, said he was being held in the hospital’s coronary unit, but declined to give further details about his client’s health.

Martinelli, 66, “was evaluated immediately by medical personnel in the prison system and paramedics … who determined that he was in stable condition,” the country’s prison system said in a statement, adding that Martinelli had been transferred to receive more rigorous testing.

The former supermarket tycoon, who was president from 2009 to 2014, has been held in El Renacer prison on the Panama City outskirts since June after being extradited from the United States to face charges that he used public money to spy on more than 150 political rivals during his presidency.

He has maintained his innocence and has said he is a victim of political persecution by current President Juan Carlos Varela, a former political ally. (Reporting by Elida Moreno; Writing by Julia Love; Editing by Peter Cooney)