THE MYSTERIOUS car wreck that took the life of Cuban dissident Oswaldo Payáand his associate Harold Cepero last year occurred on an isolated road outside Bayamo, in Cuba’s eastern Granma province. Mr. Payáand Mr. Cepero were heading to Bayamo to meet with members of the Christian Liberation Movement in a blue 2010 Hyundai Accent, a rental car driven by a young Spanish politician, Ángel Carromero, who was visiting Cuba to support Mr. Payá and his movement. Mr. Carromero survived, as did Jens Aron Modig, of Sweden’s Christian Democratic Youth movement, who had joined him on the trip to Cuba.

The official Cuban version of the accident was that Mr. Carromero was driving too fast, lost control and hit a tree. But a detailed complaint filed by Mr. Paya’s widow, Ofelia Acevedo, and his daughter, Rosa Maria, before the Spanish National Court earlier this month tells a different and more ominous story.

They say that when Mr. Carromero and Mr. Modig met in Havana with Mr. Payá and Mr. Cepero on July 20, 2012, they were monitored and followed by Cuban security agents. They were followed again when they departed Havana for Bayamo two days later. On the road, the Hyundai was rammed from behind “premeditatively, deliberately and following the plan orchestrated by the authorities,” which was to kill all four of them, the complaint says. Mr. Carromero told us in March that the vehicle that rammed the Hyundai had government license places. Soon after the crash, the ramming was reported to a person in Sweden by a text message sent from Modig’s cell phone.

The ramming was not part of the Cuban official version. Mr. Carromero’s “confession” that he was at fault was coerced by the Cuban authorities, according to the complaint. Two Cuban security agents, identified as Col. Salinas and Col. Llanes, pressured Mr. Carromero “in a direct, deliberate and conscious way” to falsify testimony during a subsequent trial that was a “farce,” according to the complaint. Mr. Carromero was convicted of vehicular homicide; he later was released to serve out his sentence in Spain. In his comments to us, Mr. Carromero recalled a nightmarish aftermath of the crash in which he was drugged, interrogated and forced to make a videotaped confession in which he read words written out for him by a Cuban security agent.

The Spanish National Court, La Audiencia Nacional, is empowered to order investigations abroad under the concept of “universal jurisdiction,” that some crimes are so egregious they must be pursued across borders, including genocide and crimes against humanity. Spain has an obligation to Mr. Payá, who was a Spanish citizen; his family argues the Castro regime has not only silenced a critic but attempted to wipe out his movement. The Spanish court ought to order an investigation. It is unlikely that the thugs who rammed Mr. Payá’s car will be called to account, but an investigation would show the world, and the Castro brothers who rule Cuba, that a beacon of hope like Mr. Payá cannot be simply extinguished in a violent car wreck on a lonely road.