An alleged far-right sympathiser was arrested in Germany on suspicion of murdering a senior local politician known for his pro-migrant views, the federal prosecutor's office said on Monday.

Walter Luebcke — a member of Chancellor Angela Merkel's Christian Democrats party — was found lying in a pool of blood on the terrace of his home in the state of Hesse two weeks ago. He had been shot in the head.

On Sunday, police special forces arrested a 45-year-old man in the town of Kassel, about 20 km from where Luebcke was found, based on DNA evidence gathered at the scene.

But the prosecutor's office said 55-year-old Stefan E., arrested on Monday, was suspected of having killed Luebcke.

"Based on the current state of investigations, we believe there is a right-wing extremist background to this act," spokesman Markus Schmitt told reporters in Karlsruhe.

He added there was no evidence that the suspect had had accomplices or that he belonged to a far-right criminal network.

Luebcke had become the subject of far-right news portals for speaking out in defence of Merkel's decision to welcome around a million refugees at the height of the migrant crisis.

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