A forensic scientist who was due to give evidence at the "Operation Puerto" trial examining Spanish doctor Eufemiano Fuentes' involvement with a number of high-profile cyclists has died, a lawyer said on Wednesday.
Francisco Aguanell examined former rider Jesus Manzano after he claimed to have worked with Fuentes and his testimony was expected to be key in determining whether the transfusions had a detrimental affect on the long-term health of his clients.
"He died yesterday morning (Tuesday) due to a severe heart-attack," confirmed Manzano's lawyer, Carlos Sanchez Peribanez.
Aguanell, 52, had been due to give evidence on Wednesday to the trial in which Fuentes is charged with endangering public health by performing blood transfusions.
However, his report on his examination of Manzano carried out in December will still be read to the court, Peribanez added.
Manzano was also due to testify on Wednesday.
Fuentes is on trial with his sister Yolanda and three other defendants from cycling teams in one of the most high-profile cases in sport over a blood doping racket, with dozens of suspects in cycling and possibly other sports.
The five are accused of endangering public health but not incitement to doping, which was not a crime in Spain at the time of their arrests in 2006.