As it continues to fight a losing public-relations battle over the ongoing diesel-emissions scandal, Volkswagen is preparing to release the results of an internal investigation of the matter.

The report on the use of "defeat device" software to cheat on emissions tests is to be released "in the second half of April," it said.

But VW has also postponed its annual shareholder's meeting, originally scheduled for April 21, to June 28.

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The report will be released by the end of April, it said, and it will hold its yearly Press Conference and Investor and Analyst Conference on April 28. That event was originally scheduled for March 10.

German law, however, requires companies to publish their annual results no later than four months after the close of their financial year, meaning April 30.

According to a release issued February 1, the postponement is due to "remaining open questions and the resulting valuation calculations relating to the diesel emissions issue."

"In this regard," it said, "Volkswagen will achieve the best possible transparent and reliable outcome for its shareholders and stakeholders."

Bloomberg suggested in its coverage of the postponement that it indicates VW simply doesn't yet know how much the scandal will cost it.

Postponing a scheduled annual shareholder meeting is a major and serious step by a huge global corporation.

But uncertainty about the ultimate costs of North American updates or buybacks for almost 600,000 vehicles has only grown since mid-January.

That's when the California Air Resources Board rejected VW's proposal for updates to 482,000 2.0-liter diesels--325,000 of which might have to be bought back from their owners--for lack of sufficient detail.

2009 Volkswagen Jetta TDI

2009 Volkswagen Jetta TDI

EDITOR'S NOTE: This first version of this story, published on Tuesday, February 2, said Volkswagen would release its internal investigation into the diesel-cheating scandal during VW Group's annual shareholder's meeting on April 21.

On Friday, February 5, the company said it would postpone that meeting, but that it would still release the report on that date. A few weeks later, VW executives said the report would be issued by the end of April.

On Friday, March 4, VW Group AG announced that it would hold its Annual Press Conference, and the accompanying Investor and Analyst Conference, on April 28 in Wolfsburg.

It also said its Annual General Meeting for shareholders would be rescheduled for June 28 in Hanover. We have updated several parts of this story to reflect these developments.

The company's top committee were to meet for the third time in three weeks on Wednesday, February 3, sources familiar with the matter told Reuters under the condition of anonymity.

(That meeting may be when the decision to postpone was made, although it was not announced by VW until very late on Friday afternoon.)

2015 Volkswagen Golf TDI

2015 Volkswagen Golf TDI

The executive committee of Volkswagen's supervisory board has been meeting more frequently in preparation for the release of the investigation results, as well as the release of the company's 2015 financial results in March, the sources said.

Officials are reportedly still determining how to account for the scandal in the 2015 results.

The six-member executive committee includes Volkswagen chairman Hans Dieter Poetsch, IG Metall union chairman Joerg Hofmann, works council boss Bernd Osterloh, deputy works council boss Stephan Wolf, Porsche chairman Wolfgang Porsche, and Stephan Weil--prime minister of VW's home region of Lower Saxony.

2015 Volkswagen Golf TDI SE

2015 Volkswagen Golf TDI SE

It is understood that the investigation, conducted by U.S. law firm Jones Day, includes testimony from around 50 Volkswagen employees, who testified under amnesty granted by the company to induce them to talk.

Germans newspapers have reported that one employee testified that VW's use of "defeat device" software was an "open secret"--something VW denies.

ALSO SEE: VW Diesel Cheating An 'Open Secret' In Engine Group: Report

The company has said the implementation of emissions-cheating software was the work of only a handful of engineers, and was done largely without the knowledge of management.

In statements to reporters last week, VW Group CEO Matthias Müller implied that the newspapers' account is untrue.

He also reinforced that the results of the probe will not be released any sooner than the April shareholder meeting.

2015 Volkswagen Golf TDI

2015 Volkswagen Golf TDI

"Is it really so difficult to accept that we are obliged by stock market law to submit a report to the AGM on April 21," Müller said last week, "and that it is not possible for us to say anything beforehand?"

While the internal report will shed some light on how an entire generation of diesel cars came to be equipped with "defeat device" software, U.S. owners remain no closer to knowing when and how their cars will be recalled.

MORE: VW Internal Diesel-Cheating Probe: So Far, 50 Employees Have Talked (Dec 2015)

VW hasn't discussed any further action since a proposal for the 482,000 cars with 2.0-liter four-cylinder engines was rejected last month by the California Air Resources Board and U.S. Environmental Protection Agency.

Officials from Audi and Porsche have indicated the 85,000 vehicles equipped with 3.0-liter V-6 engines can be made compliant with software changes and new catalytic converters--but no proposed plan for this has been submitted to regulators yet.

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