CARACAS — A Venezuelan Navy captain accused by the government of plotting a rebellion has died in custody a week after his arrest, underlining President Nicolás Maduro’s increasingly ferocious repression campaign amid a spiraling economic crisis.

The captain, Rafael Acosta, is the first of more than 100 active and retired Venezuelan officers jailed by the government on treason charges to die in custody after allegations of torture.

A military judge told Captain Acosta’s legal team on Saturday that the officer had died in a military hospital the previous night, said his lawyer, Alonso Medina Roa. Captain Acosta was detained on June 21 and charged with treason and conspiring to rebel. He denied the charges.

Mr. Medina Roa said the captain had been detained in good health but was in a wheelchair when he was brought into a courthouse on Friday. The lawyer said his client was struggling to speak or move, showed visible signs of beatings, and kept repeating the word “help” to his legal team.