BERLIN (AP) — German lawmakers on Thursday lifted the parliamentary immunity of a leading far-right politician as part of a probe into alleged tax irregularities.

Lawmakers were asked to lift the immunity of Alexander Gauland, the parliamentary co-leader of the far-right Alternative for Germany party, to allow for “search and seizure decisions ordered by a court” to be carried out.

German weekly Der Spiegel reported that prosecutors in Frankfurt are investigating whether Gauland, 78, failed to submit his personal taxes correctly.

Lawmakers also lifted the immunity of a member of Chancellor Angela Merkel’s Christian Democrats amid allegations that the member and others engaged in paid lobbying for the oil-rich nation of Azerbaijan.

The probe against Gauland is separate from an investigation into his fellow Alternative for Germany leader in parliament, Alice Weidel, who is under scrutiny over possible illegal party funding. She denies the allegation.

Gauland was criticized earlier this week for appearing to sleep during a speech given by Israeli President Reuven Rivlin to the German parliament marking 75 years since the liberation of Auschwitz. Gauland once referred to the Nazi era as a speck of “bird poop” in German history, a comment he later expressed regret for.