German police have been continuing intensive investigations into the shooting death of regional politician Walter Lübcke, after a man taken in for questioning in connection with the incident was released on Sunday.

Police said they interrogated the man, who was detained on Saturday afternoon, for several hours but that this had not produced any indications that he was involved in the death.

The mass-circulation Bild newspaper has meanwhile claimed that a police operation on two ferries traveling from near the northern city of Wilhelmshaven to the island of Wangerooge was connected with the Lübcke case. Bild cited a witness who said two men and a woman had been taken away by police and that the ferry had been searched.

Police confirmed only that ferries to Wangerooge had been delayed by an operation carried out "for another German state" than Lower Saxony, where Wilhelmshafen is situated. The village where Lübcke lived and met his death, Istha, is in the state of Hesse — some 330 kilometers (2t05 miles) away by road.

Read more: Germany: Killing of Kassel district president leaves locals aghast

Leads from the public

Lübcke, who was the president of the regional council of Kassel,  was found dead on the veranda of his house in Istha  just over a week ago. An autopsy showed that he had suffered a gunshot wound to his head, inflicted at close range. Police said there was no indication of suicide.

A spokesman for state prosecutors said police were looking at telephone evidence, photos and videos, and that members of the public had been providing dozens of possible leads. The case was featured in public broadcaster ZDF's interactive crime program "Aktenzeichen XY ... ungelöst" ("Case Number XY ... Unsolved") on Wednesday evening.

A political motive for the death has not been ruled out, given that Lübcke had previously received death threats for standing up to the far right: At the height of the massive influx of migrants and refugees to Europe in 2015, Lübcke had said it was morally right to give protection to those in need.

Police have also looked into hateful social media comments posted after his death.

tj/msh (AFP, dpa)

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