MADRID- Former mountain bike rider Alberto Leon, accused of forming part of two separate doping rings in Spain, was found dead Monday, a spokesman for the Civil Guard said.

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The 37-year-old Leon was one of 14 people implicated in the Spanish Civil Guard's anti-doping investigation Operation Galgo that cited him as a supplier of performing enhancing drugs.

Leon had also been implicated in Operation Puerto, a doping investigation that began in 2006 and led to the banning of cyclists Alejandro Valverde and Ivan Basso.

A Civil Guard spokesman from San Lorenzo del Escorial - the town near Madrid where Leon lived - confirmed his death to The Associated Press on Monday. The spokesman would not give his name in compliance with departmental rules.

Spanish newspaper El Pais reported that the former mountain bike racer had hung himself at his home, but the spokesman would not confirm details of his death.

Leon was among 14 people detained last month in Operation Galgo, which has shaken up the Spanish athletic world, with a number of coaches and athletes accused of using drugs or acting as suppliers, including world steeplechase champion Marta Dominguez. Police discovered steroids, hormones and bags of blood in raids all over the country.

Operation Puerto was the biggest doping investigation in cycling history, with more than 50 cyclists implicated following raids in May 2006 that netted steroids, blood bags and blood doping equipment.

Leon and four others detained in the case - including the doctor at the center of the operation, Eufemiano Fuentes - escaped punishment as the law did not consider doping a crime against health at the time.

Spain passed anti-doping legislation after Operation Puerto making those caught promoting drugs in sports eligible for jail terms.