German prosecutors say they have found no evidence that a federal police officer abused two immigrants while they were in custody, but have charged the 40-year-old with unrelated weapons violations and possession of child pornography.

Hannover prosecutors began their investigation a year ago after two colleagues of the officer reported he had boasted on social media that he had abused an Afghan and a Moroccan while they were in custody.

They said Tuesday they had found no evidence the officer actually had abused the two, nor evidence of other abuse of migrants in custody.

But they said in a search of the man's home they had found child pornography and an illegal shotgun.

The man was also charged with posting a photo of the Moroccan online without his permission.