Prosecutors in Germany say they're considering taking action after learning senior politicians were tipped off to details of a confidential criminal investigation into a prominent lawmaker.

Sebastian Edathy led a parliamentary panel investigating why security services failed to stop a neo-Nazi murder spree. He resigned his seat Friday, citing health reasons, days before prosecutors searched his home and offices. Authorities haven't revealed the allegations against Edathy.

Thomas Oppermann, parliamentary leader of Edathy's Social Democrats, said Thursday that he and others were made aware of the probe last October. Oppermann says he never told Edathy.

Hannover prosecutors' spokeswoman Kathrin Soefker says investigators were "surprised and shocked" by Oppermann's comments and are discussing "possible consequences."