If this is being charged as a Class B Felony, then there is a 5 year statute of limitations after
the alleged victim turned 18. So that generally means charges may be filed as long as the victim is 23 years old or younger.
As for evidence. In order to arrest someone for a crime there must be probable cause
to believe that the crime occurred and that the person being arrested was the person who did it. So, if the alleged victim is credible, police could arrest just based on allegations. That said, it is fairly unusual for the State to file charges without more evidence, which doesn't have to be forensic (like on TV) but could be other indirect evidence that supports the victim's story.
Ultimately though someone can't be convicted of the crime unless there is evidence that convinces the trier of fact beyond a reasonable doubt. Which is usually more than a victim's testimony from an event that is 10 years in the past.
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