This sentence does not specify that the officers are police officers and therefore can be members of the police, military, civil service etc., so, "Officererne finder alle de beviser" would be more accurate than "Betjentene...."
"Officererne finder alle de beviser" should not be accepted but "Officererne finder alle beviserne" should.
Ah! So the mistake was "de beviser - beviserne". I accept that, but Duo didn't accept "Officererne" either. I have reported, but once again, thank you for replying.
So evidence in danish is both singular and plural?