It depends on whether it is federal or state. The feds have 5 year statute of limitation--it will depend on a lot of factors, but generally, that's the answer. I do a lot of child porn cases and many of them can pop out of the woodwork years after the offense because they collect evidence online, in chat rooms, etc. Best advice: NEVER download anything that is even close to child porn. The federal and state law can require lifetime sex offender registration and severe jail time.
Like Mr. Solis I do a lot of CP cases. He is correct. If there is any doubt, don't open it. Simple.
This post is for information purposes only and does not constitute legal advice, nor does it establish an attorney client relationship with Mr. Cassara.