In the majority of cases instrument is not marked; instrumental constructions can be called double object constructions. There are also cases when the instrument is expressed be a special adverb going back to a Russian case-form, e.g. parkam 'with a stick' (from Russian palkoj = Instr. case from palka 'stick').
Source: Perekhvalskaya 2008: 267
Source: Perekhvalskaya 2008: 274