Mexican authorities have arrested a man in relation to the disappearance of two Australians and a US national, the Attorney General of Baja California said on Sunday.
Elena Andrade Ramírez said that the man, only named as Jesus Gerardo N alias "El Kekas," was behind bars, while two other people in custody for federal crimes may also be directly or indirectly involved.
Andrade Ramírez said there was a "high probability" that three bodies found in a well more than 15 metres deep in an area south of Ensenada, a port city on the Pacific coast of Mexico's Baja California peninsula, may be of the three missing tourists.
The bodies were yet to be formally identified.
The prosecutor said that a fourth body also found in the same well did not appear to be related to the case. Investigations were ongoing to identify the body and whether it is connected to any other investigation that is being carried out.
Australian Foreign Minister Penny Wong at the weekend said her department was providing support.