A top Brooklyn assistant district attorney who resigned this week won’t be flagged for ethical breaches in a sensational rape case that’s now on the ropes, DA Charles Hynes said yesterday.

Lauren Hersh, who led the sex-trafficking unit under Hynes, quit Wednesday amid allegations prosecutors improperly failed to disclose to defense lawyers that an alleged rape victim recanted in 2010.

Yesterday, Hynes said a review of Hersh’s handling of the case showed there wasn’t enough evidence to sanction her.

Also, a source also told The Post that other sex-trafficking investigations supervised by Hersh are not in danger of being wrecked.

Hersh quit weeks after a high-profile case, in which four black men were indicted for preying on a troubled Orthodox Jewish woman from Crown Heights, began crumbling, with two of the accused rapists being released from jail last month.