Any way to disprove a hit and run?

my dad got into a car accident lately, some kid ram into my dad's car, my dad got out of the car and ask if the kids alright and he said hes fine, but his bike was total, and he ask for $50 for the bike. being careless my dad pay him $50 the kid told my dad that he will ok and told him to leave, later after 2 hours some cop came by my house and told us that my dad was involve in a hit and run and the kid is in the hospital, apparently the kid call the cops after my dad left, saying a car hit him and ran off so he would be able sue my dad, ofc the kid didn't have any broken leg or anything, the cop said we have to prove that my dad did got out of car and check on the kid to prove that it was not a hit and run, beside the witness, which we cant find is there anyway to prove it was an accident?