Allegation of spitting but no dna (silva) found, but someone said u did. can u be prosecuted without dna?

A friend of mine was reported to the Police for allegedly spitting on someone. His friend told Police that my friend spat in his face and on his jumper. However, dna was taken from his jumper but nothing found. My friend still has to attend court because the allegation was made but no dna found. Is this right on just someones allegation?