Ultimately, Vance overruled his own prosecutors. Three months after the meeting, he told them to drop the case. Kasowitz subsequently boasted to colleagues about representing the Trump children, according to two people. He said that the case was “really dangerous,” one person said, and that it was “amazing I got them off.” (Kasowitz denied making such a statement.)
Vance did return the $25,000 donation before he met with Kasowitz, but:
Just before the 2012 meeting, Vance’s campaign had returned Kasowitz’s $25,000 contribution, in keeping with what Vance describes as standard practice when a donor has a case before his office. Kasowitz “had no influence and his contributions had no influence whatsoever on my decision-making in the case,” Vance said.
But less than six months after the D.A.’s office dropped the case, Kasowitz made an even larger donation to Vance’s campaign, and helped raise more from others — eventually, a total of more than $50,000. After being asked about these donations as part of the reporting for this article — more than four years after the fact — Vance said he now plans to give back Kasowitz’s second contribution, too. “I don’t want the money to be a millstone around anybody’s neck, including the office’s,” he said.
Both parties deny the contributions had anything to do with the case. Read more about the case at ProPublica

So, the District Attorney in New York State, a liberal democrat, governed by another liberal democrat, abandoned a pretty much closed book guaranteed conviction of two celebrities that are the daughter and son of the Democrats number 1 target in the universe.
Sorry, your story and your source are not credible.
Paid a visit to the DA AND a hefty campaign contribution (which was returned after it was discovered, of course).