Updated

The family of late Cuban dissident Oswaldo Paya will launch a lawsuit in Spain after a Spanish politician said he did not die in a car crash but was "assassinated" by Cuba's secret services, Paya's brother said Tuesday.

Carlos Paya told AFP that the family would file a complaint with Spain's top criminal court, the National Audience, since his brother had both Spanish and Cuban citizenship.

"We want the truth because we have had doubts since the beginning," he said.

Oswaldo Paya and another Cuban dissident, Harold Cepero, died on July 22, 2012, in southeastern Cuba after their rental car went off an unpaved country road and crashed into a tree.

The driver, Angel Carromero, a leader of the youth wing of Spain's ruling Popular Party, and another passenger, Swedish activist Jens Aron Modig, survived the crash.

An official Cuban enquiry found that Carromero had been driving above the speed limit at the time of the accident, causing him to lose control of the vehicle.

He was convicted in Cuba of vehicular homicide and returned to Spain to serve a four-year sentence.

But in an interview published Monday in Spanish newspaper El Mundo, Carromero said the official version that he was speeding was "a perfect alibi" to hide the fact that "Cuban secret services assassinated Oswaldo Paya".

"I am convinced that he survived the accident. The nurses and a priest told me that all four of us were admitted to the hospital," he added.

In an interview with the Washington Post in March, Carromero had already said that the car was struck from behind by another vehicle just before the crash.

Paya's family have always said they suspected the Cuban authorities of involvement in his death and have demanded an international investigation.

"Angel Carromero's testimony is important because he is the main witness and he is also a victim. But there are many witnesses," Carlos Paya said.

"We have information from other people who say that Oswlado did not die in the crash as the Cuban government claims. It is incomprehensible that, according to people who saw his cadaver, his body was intact and the head was destroyed," he added.

Carlos Paya did not say who the target of the lawsuit would be or when it would be launched.

Oswaldo Paya was the lead organiser of the Varela Project, a signature-gathering drive asking authorities for a referendum on guaranteeing rights such as freedom of speech and assembly in Cuba. He was 60 when he died.