(Adds details, background)
By Tomas Bravo
MEXICO CITY, Dec 18 (Reuters) - An ex-governor of the Mexican state of Jalisco was shot dead early on Friday in the bathroom of a restaurant in the beach resort of Puerto Vallarta, the latest violence to convulse a region plagued by drug gang violence.
Jalisco state officials said former governor Aristoteles Sandoval was shot in the back by an unidentified assailant while his security detail were outside the restaurant. A shootout erupted as his bodyguards began moving Sandoval to hospital.
Sandoval's 2013-18 term as governor was overshadowed by the brutal rise of the Jalisco New Generation Cartel (CJNG), an outfit with local roots which went from relative obscurity to become one of the most powerful drug gangs in the country.
Jalisco state attorney general Gerardo Octavio Solis said the 46-year-old Sandoval had been with three other people at the restaurant in central Puerto Vallarta, and was gunned down at around 1.40 a.m after getting up to go the bathroom.
One of Sandoval's bodyguards was seriously injured in the gunfight, Solis told Mexican radio.
The attorney general said the restaurant had "manipulated" the crime scene, cleaning up finger prints and taking security cameras in an apparent attempt "to evade justice."
He said investigators believed 8-10 suspects were involved in the attack, but did not indicate who was responsible. A federal official said authorities suspected CJNG involvement.
Mexican President Andres Manuel Lopez Obrador offered his condolences and vowed to bring the perpetrators to justice.
"It is a matter that will be investigated so that the motive is known and those responsible are punished," said Lopez Obrador during a regular morning news conference.
Sandoval's term in Jalisco got off to a bloody start, with his minister for tourism shot dead in state capital Guadalajara by suspected CJNG gunmen just a week after he took office.
The gang became an increasing menace, and in May 2015, authorities launched a botched attempt to capture CJNG boss Nemesio "El Mencho" Oseguera, which ended with the shooting down of a military helicopter by cartel henchmen in western Jalisco.
Oseguera remains at large.
Mexico has suffered record homicide levels under Lopez Obrador, in part owing to the CJNG's turf wars. (Reporting by Tomas Bravo, Raul Cortes and Laura Gottesdiener; Editing by Dave Graham, Alison Williams and Nick Macfie)
Our Standards: The Thomson Reuters Trust Principles.