Appearances in CoD:
He first appeared in V11C3 when he was providing an autopsy report to Mal Fallon and Carlito Flores. He was studying the victim of the Brujo, a killer later killed in the chapter. He then relayed a message of hope from Jacob Fallon to Mal in V11C3's bonus scene.
Then in V11C5, Luis agrees to help Mal escape by setting up a scheme where he would use a pin to un-handcuff himself and then escape the interrogation room and run to a gate that he would open at a certain time. Unfortunately, the plan failed and only Gabriel Soto left.
In V11C7's bonus scene, Luis Villareal was tortured for information (unsuccessfully) by General Salazar for information on where the Fallons were. Salazar commented that he had "always wanted to kill Villareal". He refused to divulge, and he went as far as to crack jokes as Salazar used a plier to cut teeth out of his mouth.
He was revealed to be bloodied, but still very much alive, in V11C8's bonus scene.