According to Bild am Sonntag, a top engineer at Berlin's new international airport (BER) collapsed in May 2015 while at work.  

The man survived, but a report on the cause of his collapse found that he had been poisoned, and posited that “a lethal substance could have been poured into his coffee”.

He may have been targeted for being a whistleblower in a corruption scandal that has engulfed the airport management over the past 12 months, Bild am Sonntag reports.

Now prosecutors in Brandenburg are investigating “the suspicion of grievous bodily harm”, according to Berlin daily Tagesspiegel.

The scandal relates to the construction contractor, Imtech, which prosecutors allege bribed airport officials to receive inflated payments for their work. BER as well as Imtech managers are currently under investigation for corruption.

Imtech has since filed for bankruptcy and in 2015 four people were arrested in relation to the probe, one from BER and three from Imtech.

The airport was originally supposed to open in 2011 but has been mired in a seemingly never-ending series of scandals relating to financing and planning failures.

The complete rebuilding of its fire safety systems has delayed the project for the past five years.

Airport administrators insist it will open its doors to the public at the end of 2017, but their own press officer cast doubt on this date before being promptly fired. Meanwhile a former project leader said last week that it may never open.

Accusations of contractors submitting inflated bills have also been made against Siemens, Bosch and Deutsche Telekom. In the Siemens case, prosecutors are looking into the allegation that the company charged €1.9 million for work that was never done.