Both articles mention he was fishing or after mollusks. I found the police report that suggests he was compressor diving (not scuba). Here's my translation:
"He jumped into the water and in less than a minute he surfaced, he (perhaps a fellow fisherman) saw the hose was cut. When he was pulled up they realized he was missing a leg and part of his lower belly, so they took him to Puerto Peñasco.
Police experts and Santa Cecilia funerary services arrived (met them at the Port?) and the boat Lidia Isabel was taken into custody by the Ministerial Agency of Criminal Investigation. "
Here's the link to the
article in Spanish.