There is no statute of limitations on seeking back child support payments in Florida. However, the court may apply something called "laches," which means the court decides if you have delayed without good reason and whether you have actually been prejudiced by his failure to pay.
My response to this question does not mean I agree to represent you in any proceedings. This information is also not subject to attorney-client privilege.
First I want to say sorry for your loss. I too lost a minor child and I know how it feels. That said, you should check with the Department of Revenue in the State of Florida. This government entity assists parents obtain child support and child support arrearages. The services are free. You will have to get the address of your ex-husband (there are many ways to do this online for minimal fees).
I agree with the first attorney who answered in that the biggest argument is laches, but I think since he was in prison and you probably had difficultly finding him you can argue against it.
The Department of Revenue has many ways to assist you. They can file a Motion for Contempt and if he has the ability to pay (i.e. has a job or assets) ask that he pay a purge (lump sum of money) or go to jail. Most come up with the money. They can also, if he is employed, garnish his wages through an Income Deduction Order. They can also do other things like prevent him from getting a passport or suspending the one he has, place a lien upon his tax returns so you get those monies, suspend his driver license, etc.
However, the downside to the Department of Revenue is that the process takes forever. So if you want to consider this, do it NOW!!!! Don't wait. Good luck.
Penny Taylor-Miller, Esq.
8551 W. Sunrise Blvd.
Legal disclaimer: This answer is offered for informational purposes only. It is not offered as, and does not constitute, legal advice nor does it constitute an attorney-client relationship