Prosecutors for special counsel Jack Smith have been asking questions in recent weeks about the handling of surveillance footage from former President Donald Trump’s Mar-a-Lago resort after the Trump Organization received a subpoena last summer for the footage, according to multiple sources familiar with the investigation. The handling of the footage, and how employees within the Trump Organization responded to the Justice Department’s demand for it, have prompted a new round of grand jury subpoenas to top Trump employees in the last few weeks, the sources told CNN. Longtime Trump Organization executives Matthew Calamari Sr. and his son Matthew Calamari Jr. are expected to appear Thursday before the grand jury investigating possible mishandling of classified documents brought to Trump’s Mar-a-Lago home, sources said. Prosecutors are expected to ask them about the handling of the surveillance footage and Trump employees’ conversations following the subpoena, according to the sources. Calamari Sr., the executive vice president and chief operating officer of the Trump Organization, has primarily overseen security operations for Trump and his properties during his decadeslong career working for Trump. His son, Calamari Jr., is director of security for the Trump Organization. An attorney for Calamari Jr. declined to comment, as did a spokesman for the special counsel’s office. An attorney for Calamari Sr. did not respond to a request for comment. The grand jury activity scheduled for Thursday marks another step forward for Smith’s investigation, as it secures some of Trump’s closest allies as witnesses potentially against him. The footage has been a part of the Justice Department’s investigation into possible mishandling of classified records at the Florida beach club after Trump left the presidency and possible obstruction of justice. No charges have been brought in the case, and Trump has denied any wrongdoing. CNN has previously reported the footage captured Walt Nauta, an aide close to the ex-president, Nauta and another Mar-a-Lago employee moving boxes containing documents out of a storage closet. The Calamaris are among several witnesses expected to testify in Smith’s investigation on Thursday, sources said. Prosecutors have previously brought in lower-level Trump employees for questioning about the surveillance footage, including how it may have been handled in response to the subpoena for it and if it could have been tampered with, two sources told CNN this week. Investigators also have previously asked about a text message from Nauta to Calamari Sr. and subsequent conversations about the surveillance footage, according to two of the sources. The Justice Department questioned Nauta months ago about the handling of the boxes, and he told the FBI about being directed by Trump, CNN previously reported. A lawyer for Nauta declined to comment.