More than three years after the blackmail cases at the parcel delivery company DHL, a man reported to the Potsdam public prosecutor.
This was confirmed by the Chief Public Prosecutor Wilfried Lehmann on Wednesday evening.
"A man got in touch with us and we are now checking his details," said Lehmann of the German Press Agency.
Several media had previously reported on it.
According to dpa information, the man accused himself of the acts.
The investigators now want to check whether the man actually has knowledge of the perpetrator or whether it is possibly a so-called free rider.
On December 1, 2017, a package bomb was discovered in a pharmacy in Potsdam.
It also contained a letter extorting DHL.
The sender asked for twelve million euros in bitcoins.
It later emerged that the blackmailer's first package had been discovered in Frankfurt Oder in November.
Two more shipments were sent to Berlin in January and April 2018.
The State Criminal Police Office investigated the suspicion of causing an explosive explosion as well as the severe extortion by robbery.