Taveras, who ran Mar-a-Lago’s technology department from a cramped work space in the basement of the sprawling Florida property, confided in an office mate that another colleague had just asked him, at Trump’s request, to delete the footage that investigators were seeking. Taveras had balked at what prosecutors said was Mr. Trump’s request. He was unwilling to cross a line and potentially go to prison. Still, when he was summoned before a grand jury this spring, Taveras did not fully recount the incident. Only after prosecutors subsequently threatened to charge him for failing to tell all that he knew did Mr. Taveras shift course to become a potentially important witness in the case. Facing indictment this summer, Taveras replaced his lawyer, who was being paid by Mr. Trump’s political action committee. Taveras then returned to the grand jury and offered a more detailed version of events, recounting how he had been asked to delete the surveillance footage. In exchange, prosecutors agreed not to charge him. Taveras is expected to testify against the former president as well as two of Mr. Trump’s employees, Walt Nauta and Carlos De Oliveira, all of whom were charged with a conspiracy to obstruct the government’s investigation. A native New Yorker with a love of music, Taveras once worked as a D.J. but came to focus on computers. He has worked for Trump for 13 years, first in New York before eventually earning a promotion.