MANILA - The fatal shooting of the lawyer of a mayor who was linked by President Rodrigo Duterte to the illegal drug trade could have been motivated by the victim's alleged involvement in criminal gangs, police said.

Lawyer Rogelio Bato Jr. was reportedly involved in the operations of Ronald "Kerwin" Espinosa, a suspected drug lord in the Western Visayas and son of Albuera town Mayor Roland Espinosa, police said.

Albuera police chief Jovie Espenido said he had reprimanded Bato for his alleged involvement in drug trafficking.

"Sinabihan ko siya na sayang ang profession niya... Marami ka namang pera na makuha hindi lang sa illegal drugs," Espenido said. [I told him that he's wasting his profession... There are many other means of earning money outside of the illegal drug trade.]

Unidentified assailants shot Bato while he was driving in Tacloban City on Tuesday. His female companion, who was identified as a 16-year-old student, also died.

The lawyer was among the top contributors to Espinosa's campaign funds in the May elections, based on a statement of contribution and expenditures (SOCE) obtained by ABS-CBN News.

Espinosa surrendered to the Philippine National Police (PNP) last month and admitted that his son is a drug trafficker.

With no arrest warrant against him so far, the the mayor allowed to return to work. The younger Espinosa remains in hiding. -- With a report from Ranulfo Docdocan, ABS-CBN News