The "Task Group Mariano" is headed by Senior Superintendent Wifredo Abella, deputy director for operations of the Ilocos Norte police, and composed of representatives of the Criminal Investigation and Detection Group, National Bureau of Investigation, the San Nicolas police and other law enforcement agencies.
The task force will concentrate on three possible motives: Marianos exposés on jueteng, alleged anomalies at the Ilocos Norte Electric Cooperative (Ineco) and his alleged involvement in a murder case in 1999.
A police official, who declined to be identified, said Marianos killers appeared to be very angry with the radioman who sustained 15 bullet wounds, four of them in the head.
Mariano, 44, was on his way home aboard a motorcycle after completing his broadcast at dzJC Radyo Natin-Aksyon Radyo when he was shot in the head and back.
Meanwhile, the Ilocos Norte provincial board has passed a resolution condemning Marianos killing and urging authorities to speedily solve the case.
In a statement, the New York-based Committee to Protect Journalists (CPJ) said it was investigating the motives behind Marianos murder to determine whether they were related to his journalistic work.
It noted that since 1986, 43 Filipino journalists have been killed for their work, and that no one has yet been prosecuted for any of these killings.
"Philippine authorities must act to end a culture of impunity that has made it unsafe for journalists to work," said CPJ executive director Ann Cooper. Vic Alhambra Jr., Teddy Molina and Christina Mendez