The Manhattan district attorney is delving deeply into the personal and financial affairs of the chief financial officer for former president Donald Trump’s company, probing the extent of Allen Weisselberg’s loyalty to Trump and scrutinizing a Trump-owned apartment once occupied by Weisselberg’s son, according to people familiar with the investigation.

This questioning is now led by a former mob prosecutor, and one person familiar with the investigation said it is aimed at “flipping” Weisselberg — attempting to turn one of Trump’s longest-serving and most important aides into a witness against him…

Vance’s focus on Weisselberg has included questions related to two of his adult children, a tactic that could be an effort to increase pressure on the elder Weisselberg. One of Weisselberg’s sons also works for the Trump Organization, where he manages the company’s Central Park ice rinks. Another Weisselberg son works for a company that has extended loans to the Trump Organization.

Vance recently obtained millions of pages of Trump’s tax and financial records. Now he appears to be focused on their human equivalent: a man who has paid Trump’s bills and kept his books since the 1980s.