Image source: Volkswagen.

Last week, Volkswagen's(VWAGY -1.11%) U.S. boss told Congress that, in his understanding, responsibility for VW's massive emissions scandal fell on "a couple of software engineers."

I knew that story didn't pass the smell test. 

A new report from German newspaper Speigel says that "at least 30" Volkswagen managers were involved in VW's massive emissions cheating scandal -- and the details could become public as soon as Thursday. If you have been waiting to buy Volkswagen stock until "the other shoe dropped," this could turn out to be that shoe.

A lot of people inside VW had to have known
As part of his initial response to the scandal, new VW CEO Matthias Mueller commissioned U.S. law firm Jones Day to conduct an exhaustive investigation into how exactly 11 million diesel-powered vehicles ended up with software designed to produce false-positive results on emissions tests. VW's own internal auditing department is also involved in the investigation.

Mueller is set to brief top VW executives on the state of the investigation on Thursday, but it appears that some details have leaked. Speigel, citing internal VW sources, said "several dozen" -- "at least 30" -- managers were involved in the decision to cheat -- or at least knew about the cheating and kept quiet. (You can find the report here. If you don't read German, online translators will give you the gist.)

A VW spokesperson said that the number of managers mentioned in Spiegel's report was "completely unfounded." Spiegel acknowledged VW's denial, such as it was, but the newspaper didn't retract or otherwise modify its story.

The Spiegel report notes that emissions from the "EA 189" diesel engine with the cheating software had been tested internally by VW several times since the engine first went into production in 2008. That suggests that many VW employees may have known that something wasn't right. 

The idea that the engine somehow met emissions standards without the expensive pollution-control equipment fitted to other VW Group diesels would "have to make any engine developers leery," a VW source told the newspaper.

That all makes a lot of sense. So what happens now?

We should know a lot more on Thursday
What probably happens now, assuming that the gist of the Spiegel story is correct, is that the managers implicated by the investigations will be "suspended," or put on leave -- a first move toward firing. Some may choose to depart immediately without waiting around to be fired.

(This may or may not be coincidence: VW abruptly announced the departure of longtime  executive Winfried Vahland on Wednesday. Vahland, who most recently led VW's Skoda brand, was about to take over VW's operations in North America. VW's statement said that Vahland's decision to leave was about strategy differences and "expressly not related to current events on the issue of diesel engines," but the abruptness and the timing of the decision are noteworthy in context.)

CEO Mueller is also expected to present his plan for dealing with the financial costs of the scandal, which are nearly certain to surpass the 6.5 billion euros ($7.43 billion) that VW has already set aside. Drastic cuts are likely, but the specifics aren't yet clear.

If you've been waiting to buy VW stock, wait a little longer
As investors, we know that, when a good company falls on hard times, it can represent a profitable buying opportunity. VW's stock has lost about a third of its value since news of the scandal broke last month.

Given VW's still-massive strength, that would seem like a buying opportunity -- but I've said that it might be wise to hold off until we have a better idea of the full scale of the impact to VW, financial and otherwise. We may have a much better idea after Mueller briefs executives on Thursday. 

If you've been waiting for a good moment to buy, that moment may be coming soon.