How old does a person need to be to babysit a 3 year old?

My son is 3 years old. Up until now all of his babysitters have been adults, mainly due to ready availability of college students and family. Now we’re having a little more trouble finding an available sitter, especially on short notice (obviously). My wife’s aunt called us to say that one of her grandkids has taken a baby sitting class and would like to baby sit for us. She is 13. I’m sure I had 13 year old sitters when I was a kid, and a 3 year old is much easier than even a two year old, but still requires more supervision and care than an older kid. I think she’s probably old enough to do this, but if she does are we going to end up on the evening news (negligent parents leave toddler with 13 year old sitter: what were they thinking!)?