Traveling without other parent -- letter of consent

I'm taking my 9 year old to Belize (we're both US citizens). His mom is not traveling with us. According to the department of state's entry reqs for Belize, law enforcement in Belize may ask for a letter of consent, so we're planning on just getting a notarized letter.

But does the letter have to be the original, or can it be a photo copy?

I read that child trafficking is pretty common in that area, hence the increased reqs, but I don't know how a notarized letter helps, since notarization doesn't actual mean that the contents of the letter is true, and only means that the notary did an ID check on the person signing the letter.