Investigators had hoped that the couple from Munich, who are active in right-wing circles, could have led them to the man who stabbed Passau police chief Alois Mannichl outside his home on December 13. But police said they have no concrete evidence against the man and woman. The couple had insisted they played no role in the incident.

It is another blow for investigators looking into the case. Directly after the attack, two men in the twenties from the Passau area were arrested, but released a day later due to a lack of evidence.

Police are still uncertain whether just one individual or a group is behind the stabbing. Witnesses have claimed that on the day of the attack they saw several skinheads in the municipality of Fürstenzell, where Mannichl lives. A 50-person investigative team is looking for two men suspected in the case in both Germany and Austria.

Drawings of two have been released showing men with unusual tattoos – a green snake behind one man’s left ear and a cross on his right cheek. But police say that have no information on the identity of the assailants and that one man might even have both tattoos.

On Saturday, December 13, Mannichl reportedly answered his front door to a tall skinhead at around 5:30 pm. The man said something along the lines of “Greetings from the national resistance,” and added, “You leftist pig cop, you won’t trample on the graves of our comrades anymore,” before stabbing the police chief in the stomach with a 12-centimetre knife.

He then threw the knife away in the garden and ran to a waiting car in a nearby street and was driven away.

The 52-year-old police chief, who is known for being tough on the neo-Nazi scene, was seriously wounded, but has now been released from the hospital.