German police say a man who was detained in an investigation of the fatal shooting of a regional official from Chancellor Angela Merkel's party has been released after questioning.

Walter Luebcke, who was in charge of the Kassel area regional administration, was found outside his home last Sunday by a relative. An autopsy confirmed a pistol shot to the head, fired at close range, and a homicide investigation was opened.

On Saturday, a man was taken into provisional custody in the case. But news agency dpa reported Sunday that police said he was questioned and then let go. They didn't give further details.

Luebcke in 2015 received threats after speaking out in support of helping asylum-seekers, but police have said those threats appear to have no connection to his death.