Paternity is in question

by Stella
(Hammond,LA)

My friends daughter is 23 yrs old now. He is still paying child support to his ex-wife
She has lied about money he has paid to her and keeps asking for more. He has told me that the reason they got divorced was because he caught her sleeping with his brother! He had been suspecting it for sometime. He said he never really told anyone that before. He just wondered to himself if the baby was really his.
I met her recently and Wow! She looks Just like his brother. My question is this:
we live in Louisiana- if he were to establish DNA testing that he was not the father- could he petition to be relieved of child support?