WASHINGTON (AP) — Cruising around Caracas in a convoy with five cellphones full of valuable contacts, Gen. Manuel Cristopher Figuera displayed trappings that befitted his reputation as a loyal soldier who rose from an upbringing in a dirt-floored hut to become Venezuela's spy chief.

But as President Nicolás Maduro began to lean on the brawny 55-year-old to do his dirty work — in Cristopher Figuera's telling, ordering him to jail opponents and victims of torture — the Cuban and Belarusian-trained intelligence officer gradually lost faith. In a show of nerve, he betrayed the leader he met with a...