A German far-right extremist has been sentenced to life imprisonment for murdering pro-refugee politician Walter Luebcke, a killing that shocked the country and raised questions about whether the government is doing enough to tackle right-wing radicalism.

Walter Luebcke, a member of Chancellor Angela Merkel's conservatives, was found dead in a pool of blood outside his house in the western state of Hesse in June 2019. He had been shot in the head at close range. The court convicted the defendant, Stephan Ernst, of the murder of Luebcke by shooting him.

Life imprisonment in Germany has an indeterminate length and can be changed to parole after 15 years. But the court said that, given the severity of Ernst's crime, it reserved the option to place him under a preventive detention order once his sentence had been deemed completed.

Outside the Higher Regional Court in Frankfurt, protesters held posters of Luebcke and placards reading "Open to diversity" and "Democratic values are immortal."

Luebcke became a figure of hate for the far-right because of his outspoken support for the open-door policy Merkel adopted in 2015 toward the migrants and asylum seekers who that year fled war and poverty in the Middle East and beyond in their hundreds of thousands.

The court rejected charges of aiding and abetting the killing filed by prosecutors against a second defendant, named only as Markus H. It sentenced him instead to 18 months in prison for a weapons offense.

Federal investigators said last year that 45-year-old Ernst drove to Walter Luebcke's house in Wolfhagen, central Germany, on the evening of June 1, 2019. He crept up under cover of darkness to the terrace where Luebcke sat before shooting him in the head with a revolver.

Ernst and his fellow accused had attended a political meeting in October 2015 where Luebcke argued in favor of accommodating refugees in the town of Lohfelden. At the time of his June 2019 arrest, Ernst held "several firearms and ammunition that he had acquired illegally," prosecutors said, including three revolvers, two automatic pistols, two rifles, 1,400 rounds of ammunition and a submachine gun.