for sure it is a Hemiptera. Probably indeed a  Ranatra linearis

Order- Hemiptera, Family- Nepidae, Genus- Ranatra.

Now the main things to do is to compare its morphological characters with the published keys and books. They are available online.

Cheers!!!

Ranatra species

Ranatra australis? water scorpion

In Mexico it may be different species then R. linearis. But surely it is Ranatra.

Ranatra sp.

Ranatra sp

For sure, it is belonging to order Hemiptera, family of Nepidae and Genus Ranatra sp. But, in Mexico, perhaps is différent than R. linearis.  We must use comparative morphological characters according to keys and books.