Former District Administrator Anton Graf Schwerin von Krosigk from Bad Segeberg has been missing for a week.
The ninety-seven-year-old left Bad Segeberg for Högersdorf in a black Golf last Monday, but never got there, according to a police statement.
He was reported missing that same evening.
There has been a public search for him since Tuesday.
"We are looking for him very desperately," said his niece, AfD politician Beatrix von Storch, on social networks last week.
The retiree is described as 1.80 meters tall and of slim build.
He left the house with black corduroy trousers, a dark blue striped shirt, and he is probably wearing a dark jacket.
As a police spokeswoman told the "Hamburger Abendblatt" on Friday, some tips have been received in the meantime, but the clues are not concrete.
The favorite places of the missing person will be increasingly searched.
Police could not be reached for an inquiry on Sunday.
The pensioner didn't have his mobile phone with him when he left the house on Monday evening, one of his sons told the "Segeberger Zeitung".
He also did not take his ID with him.
His father knew the five-kilometer route to Högersdorf well, there he wanted to take part in a meeting of the Rotary Club Bad Segeberg, which he co-founded.
As his niece Beatrix von Storch wrote on Facebook, it cannot be ruled out that Krosigk, who turned 97 on Thursday, got onto a federal road or motorway and "accidentally traveled far outside of Bad Segeberg".
The member of the Bundestag offered a reward of 1,000 euros for information leading to the discovery of her uncle.
Anton Graf Schwerin von Krosigk was born in 1925 in Heeren, Westphalia.
His father, Johann Ludwig Graf Schwerin von Krosigk, had been appointed Minister of Finance in the Weimar Republic in 1932 and also retained the post in Adolf Hitler's cabinet.
After the end of the war he was sentenced to ten years in prison at the Nuremberg trials.
The son studied law and in 1966 he was elected district administrator of the Segeberg district.
The independent remained in office until 1990.
Krosigk has four children, his wife died last year.