The prosecutor’s office in Frankfurt said the 56-year-old building manager, whose name has not been released, had hanged himself last Saturday with his belt despite being on suicide watch.
The suspect, who had been detained last month, had been accused of corruption and breach of trust for allegedly accepting more than €2 million (2.4 million dollars) in bribes along with other Ikea employees.
“His death will make the investigation more difficult,” a spokeswoman for the prosecutor’s office, Doris Mueller-Scheu, said.
The suicide only came to light when local media reported it.
The man was in custody along with another construction manager and two executives from a building company that worked for Ikea. Frankfurt prosecutors said there were some 20 suspects in the case.