Manhattan’s district attorney has convened the grand jury that is expected to decide whether to indict former president Donald Trump, other executives at his company or the business itself, should prosecutors present the panel with criminal charges, according to two people familiar with the development. The move indicates that District Attorney Cyrus R. Vance Jr.’s investigation of the former president and his business has reached an advanced stage after more than two years. It suggests, too, that Vance thinks he has found evidence of a crime — if not by Trump, by someone potentially close to him or by his company. Vance’s investigation is expansive, according to people familiar with the probe and public disclosures made during related litigation. His investigators are scrutinizing Trump’s business practices before he was president, including whether the value of specific properties in the Trump Organization’s real estate portfolio were manipulated in a way that defrauded banks and insurance companies,and if any tax benefits were obtained illegally through unscrupulous asset valuation.