Both men were able to provide convincing alibis and did not match DNA traces left at the scene of the crime, Walch said. Mannichl also did not recognize photos of the 26 and 27-year-old suspects.
Police now have no concrete leads in the case that has Bavarian authorities looking in far-right neo-Nazi groups for suspects.
The two suspects were arrested not far from 52-year-old Mannichl's home near Passau, where he was found slumped on his porch with stab wounds to his abdomen. Walch did not reveal the time of the arrest or the ages of the suspects due to “investigative reasons.”
Local newspaper Am Sonntag reported Mannichl answered his front door on Saturday to a tall skinhead at around 5:30 pm on Saturday. The man said something along the lines of “Greetings from the national resistance,” and said, "You leftist pig cop, you won't trample on the graves of our comrades any more," before stabbing Mannichl in the stomach with a 12-centimetre knife.
He then threw the knife away in the garden and ran to a waiting car in the nearby street and was driven away.
Senior public prosecutor Walch said Monday afternoon that the knife used in the attack belonged to Mannichl, who had apparently used it earlier to cut Lebkuchen Christmas sweets at a neighbour's party. He left the knife in his garden afterwards. Walch said police were not ruling out a premeditated crime, though.
Mannichl was seriously wounded, but declared out of danger after an operation.
Far-right resentment in the region against the police reached a high point this July after the authorities ordered that the grave of a former neo-Nazi functionary be opened so that a Nazi flag that had been buried with the coffin, be removed.
The local far-right extremist NPD party had accused the police chief of making the group feel harassed on November 16 as they marked the defeat of Nazi Germany at the end of World War II.
Bavarian State Premier Horst Seehofer said on Sunday evening that this “new dimension” of right-wing extremist violence required a “new and very clear and hard answer from the state,” adding that the Bavarian cabinet would on Tuesday discuss the possibility of banning the NPD party.