* Captain Rafael Acosta died in military hospital in Caracas * Waleswka Pérez: ‘They tortured him so much they killed him’Venezuela’s President Nicolás Maduro has ordered ‘ a full and exhaustive investigation of this regrettable event’, according to the information minister. Photograph: Carlos García Rawlins/ReutersThe wife of a Venezuelan navy captain who was allegedly tortured to death after being detained for conspiring to overthrow Nicolás Maduro has called for a United Nations investigation into his killing.Captain Rafael Acosta died at a military hospital in Venezuela’s capital, Caracas, on Friday night having been seized on 21 June during a roundup of alleged anti-Maduro plotters.Acosta’s lawyer told reporters that in the hours before his client’s death he had appeared in a military court in a wheelchair, semi-conscious and with what he called visible signs of torture.“They tortured him so much that they killed him,” his widow, Waleswka Pérez, told one Miami-based broadcaster, according to Reuters.Writing on Twitter, Pérez added: “I request international support for an independent United Nations forensic examination to determine the cause of death of the father of my children. I demand justice.”UN human rights chief Michelle Bachelet on Monday said she was “shocked” Acosta’s death and called for an independent and transparent investigation, including an autopsy meeting international standards.“This is essential to shed light not only on what happened to him, but in order to facilitate bringing to justice those responsible for his death,” Bachelet said.Maduro’s former spy chief – who recently fled the country after defecting – claimed the killing was the work of his former boss’s “butchers”.“Venezuelan brothers and sisters, this dictatorship is a danger to absolutely all of us – no one is safe,” Gen Manuel Ricardo Cristopher Figuera wrote in an open letter published on Sunday.Venezuela’s chief prosecutor, Tarek Saab, said on Monday that two national guard officers working for the military intelligence agency DGCIM had been charged with homicide over Acosta’s death, but he offered no explanation as to how he had died.The death – which Venezuelan authorities have confirmed and vowed to investigate – sparked outrage among Maduro’s political foes and members of the international coalition that has been battling since January to replace him with the opposition leader Juan Guaidó.“It is up to us to unite to bring an end to this dictatorship that tortures and kills,” Guaidó tweeted on Sunday night, denouncing what he branded Acosta’s “abhorrent” murder.The US state department blamed the captain’s “senseless killing” on “Maduro’s thugs and their Cuban advisers”, adding: “This latest act of Maduro’s barbarism must stir us to action.”Even Mexico’s government – which under the leftist leadership of President Andrés Manuel López Obrador has refused to join efforts to unseat an increasingly isolated Maduro – voiced concern that Acosta had died with “apparent signs of torture”.Venezuela’s information minister, Jorge Rodríguez, said Maduro had ordered “a full and exhaustive investigation to clear up this regrettable event”.The outcry came as representatives of Maduro and Guaidó were reportedly preparing to sit down for a fresh round of talks this week designed to quench Venezuela’s smouldering political crisis.Those discussions – expected to be held on the Caribbean island of Barbados – were set to follow an earlier three-day negotiation held in Norway’s capital, Oslo, in late May after Guaidó’s failed 30 April attempt to spark a military uprising against Maduro.But on Monday the Associated Press reported that the opposition had put the talks on hold as a result of Acosta’s death.Guaidó’s representatives did not immediately respond to requests for confirmation of the suspension.Maduro’s envoys were reported to have dismissed the opposition’s key demands – for Maduro’s resignation and free and fair presidential elections – during the first round of exploratory talks in Oslo. But some western diplomats believe Maduro’s political standing was so weakened by the alleged involvement of top officials in the botched attempt to topple him that he may be forced to make concessions.