On 10 December 2010, it was reported that Casas' former youth club, Primera División Paraguaya team Libertad would sue Panathinaikos for breach of trust.
[3] Libertad detailed that the club deserved expenses due to forming the player: "We brought him from the interior, we looked after him, we gave him food, we gave him home health, we formed him for four years to become a Libertad player and he is taken.
In November 2015, Casas featured in both fixtures of the play-off against Club Fulgencio Yegros as 22 de Septiembre were defeated 4−2 on penalties after a 2−2 aggregate score.
[7][8] Casas made his first appearance for the club in Round 1 of the 2016 División Intermedia, playing a full 90 minutes of a 3−2 away victory against Ovetense.
[13] In 2019, Casas played for Encarnación team Athletic FBC in Paraguay's third-tier.