[1] He made his debut for the East Germany national football team in an August 1978 match against Bulgaria, immediately scoring his first two goals in a 2–2 draw.

The team made a visit to the city of Gießen the day after the match, on their return trip to East Berlin.

Eigendorf's club BFC Dynamo was under the patronage of the Stasi, East Germany's secretive state police, and subject to the personal attentions of the organisation's head, Erich Mielke.

In 1983, Eigendorf moved from Kaiserslautern to join Eintracht Braunschweig, all the while under the scrutiny of the Stasi who employed a number of West Germans as informants.

An autopsy indicated a high blood alcohol level despite the testimony of people he had met with that evening which indicated that Eigendorf had only drunk a small amount of beer.

[6][7] The Stasi assigned a group of two full-time officers from the district administration to the supporter scene of BFC Dynamo during the 1982–83 season.

[6] After German reunification and the subsequent opening of the files of the former East Germany's state security service, the public prosecutor's office in Berlin started an investigation into the possible murder of Eigendorf by the Stasi, but in 2004 the case was closed.

In 2011, despite public pressure, the prosecutor's office did not see any objective evidence of third-party involvement, and suspicions of a contract killing could not be corroborated, so the case was not reopened and the allegations lingered.