A Cameroonian boat captain and his second-in-command allegedly beat and then tossed six Christian migrants overboard because they thought that their prayers were bringing storms, say Spanish prosecutors.

The trial, which started Monday, concerns an incident that took place on December 5, 2014, when a small vessel carrying 57 asylum seekers on its way from Morocco to Spain was engulfed in a storm. The captain of the ship, a Cameroonian Muslim man known only as Alain N.B., spotted a Nigerian pastor leading prayers for the safety of all on board.

Believing his prayers were making the storm worse, Alain and his friend allegedly hit the pastor over the head with a plank, then beat him and threw him overboard. They then went around the other passengers searching for amulets and other Christian symbols and upon finding them, disposed of at least five (and possibly as many as 10) other men in the same manner.

“[Alain]was aware that the victims could not possibly survive and that they would die, either by drowning, from the cold, or from the physical injuries they had suffered,” said the prosecution in its statement, according to the Telegraph. “He was aware of the low temperature, the rough seas and the great distance from the coast and the absence of any nearby boats which could rescue them.”

Of the 57 original passengers on the boat, only 29 made it alive to the port of Almeria in southern Spain. The others, including seven babies, are believed to have drowned in the storm or been killed by the captain and his friend. All are believed to be from sub-Saharan Africa.

While acknowledging the tensions onboard the ship, Alain denies the charges, claiming he is a practicing Christian and regularly attends mass at the El Acebuche prison where he is being held.

“Since I’ve been in jail I have a clear conscience and I have not taken sleeping pills,” the Europa Press agency quoted him saying. “I’ve seen other people in prison who have killed and taken many tranquilizers to sleep.”

The case against him – six counts of murder with aggravating religious circumstances – is based on the testimony of four survivors, who also accuse the two men of robbing their victims of €1,500, the amount that was found on the captain at the time of his arrest.

The 23 other passengers do not blame the captain and only one body was recovered a few days after the storm. The male corpse did not show any sign of violence and it is unclear whether the man was on the same voyage.

The second Cameroonian man, Alain’s co-accused, died in prison awaiting trial.