The FBI's investigation into the possibly corrupting influence of two businessmen's gifts on high-ranking cops and Mayor Bill de Blasio, and de Blasio's own questionable campaign fundraising, is leakier than a rowboat made out of Swiss cheese and sealed with raindrop cakes. So it should surprise no one that today brings more tidings of what the feds—and, it turns out, Manhattan District Attorney Cy Vance—are looking into.

For one, there's the developer-backed anti-horse-carriage-industry group New Yorkers for Clean, Livable and Safe Streets. Vance's office and U.S. attorneys have subpoenaed the group for documents dating back to 2013. That would include records relevant to the $100,000 the group gave to de Blasio's now-disbanded Campaign for One New York, a nonprofit that allowed his donors to give without abiding by limits on campaign contributions, but that was not supposed to coordinate with him, and $225,000 a union, run by de Blasio's cousin and a donor, gave to NYCLASS, which passed on the money to a group attacking de Blasio's Democratic rival in the 2013 primary, Christine Quinn.

De Blasio pledged to ban carriage horses "on day one" of his mayoralty. The sale of the site of the horse stables on the West Side could be a moneymaker for NYCLASS cofounder and developer Stephen Nislick. However, Nislick has said he wouldn't take the property if it was given to him. De Blasio has so far failed to pass a bill banning carriage horses, and a secret deal he hatched to only reduce the number of horses and move the stables to Central Park imploded spectacularly this February when basically everyone hated it, and everyone else was too embarrassed to keep backing it.

As the Daily News outlined in an extensive report, donors to Campaign for One New York had a way of getting what they wanted from the city. For example, developer Joe McMillan of the company DDG Partners got a zoning variance for his condo high-rise in Tribeca approved despite strident opposition from the local community board, then gave $10,000 to the nonprofit days later. Curious!

Then there's cash that de Blasio poured into upstate state Senate races in 2014 in an effort to regain a Democratic majority, and get some leverage with Governor Andrew Cuomo. According to the New York Times, "the Democratic committees in Putnam, Ulster and Monroe Counties raised at least $1.2 million in large donations from union political action committees, private companies and individual donors, state records show, and sent money to four Senate candidates in close races." Much of the fund-raising was done at the request of de Blasio and his surrogates.

Donating to local Democratic committees allowed contributors to skirt limits on what they could give directly to candidates, but donors are barred from directing the committee money to favored candidates. That doesn't mean they didn't try, though. The Times talked to committee officials for Putnam and Monroe counties who said that donors routinely tried to direct their contributions. Both claimed to have not allowed that.

The bid to take the Senate failed, but it seems to have left de Blasio in a deepening mess. He has yet to be accused of wrongdoing.

Top NYPD officials, meanwhile, got retrained recently in the very simple ethics rule on taking gifts, which is that cops can't accept anything worth more than $50. Current police Commissioner Bill Bratton got in his own trouble in 1996 for accepting trips to the Dominican Republic and Colorado from financier Henry Kravis, a scandal that, even though he had repaid the cost of the trips, directly preceded his departure from his first term as head of the department. Each of the three police commissioners since then has had gift-taking scandals of his own, one of which, around Bernard Kerik taking free renovations for his Riverdale apartment, resulted in prison time.

The latest focus in the NYPD is 20 high-ranking officers who have been questioned in connection with lavish international trips taken with businessmen Jona Rechnitz and Jeremy Reichberg, possibly in exchange for personal security details, get-out-of-jail-free cards for friends and relatives, and even a helicopter flyover for Reichberg's river-cruise party. Oh, there may have been some police boat rides for attendees at another of Reichberg's parties, a barbecue on the water in Sunset Park last summer, the News reports.

So far, nine officers have been demoted at least temporarily in connection with the steady drip-drip of publicity around the probe, and two men have been arrested, a restaurateur and friend to the NYPD accused of running a Ponzi scheme through a fictional wholesale liquor business, and an ultra-Orthodox Jewish neighborhood watch leader accused of bribing cops to obtain gun licenses.

Now, wouldn't you know it, de Blasio is getting all Bernie Sanders on campaign finance.