Police investigators obtained yesterday a list of vehicles that entered the SM Megamall pay parking area prior to last Sunday's bomb blast at the building.
The bombings left a Megamall janitor dead and at least 30 others wounded.
The probers gave assurances, however, that they are leaving no stone unturned in their search for the culprits.
The Presidential Anti-Organized Crime Task Force (PAOCTF), which has been designated the lead investigating agency, even downplayed the significance of an artist's sketch of a suspect issued the other day by the National Bureau of Investigation.
Chief Superintendent Francisco Zubia, deputy chief of the PAOCTF, said the accuracy of the sketch would largely depend on how well the witnesses could recall the facial features of the suspect.
"We can never be really sure that the sketch is that of the perpetrator unless we catch him and make a comparison," Zubia said.
The PAOCTF has invited for questioning three security guards and two male porters of the establishment who were on duty when the bomb went off.
The investigators also clarified that the blast took place at the men's comfort room of Cinema 6, not at the women's comfort room as initially reported.
Philippine National Police chief Director General Panfilo Lacson has theorized that parts of the explosive were smuggled into the mall in plastic drinking cups, and assembled before it was planted inside a blue trash can at the comfort room.
Probers said the blast at the SM Megamall was caused by a home-made C-4 plastic bomb set off by dry cell batteries.
In another development, Western Police District director Chief Superintendent Avelino Razon Jr. met with some 500 representatives of various business establishments in Manila over security arrangements regarding bomb threats.
During the one-hour meeting, Razon expressed displeasure over the private security guards' sloppy conduct of inspecting packages and bags of people entering banks, department stores and other business firms.
Razon said the guards did not know what to look for and how to go about their job.
Razon informed the private security officers that he would test the preparedness of the so-called blue guards in detecting concealed bombs by dispatching some of his policemen who would pose as bomb attackers.
Razon clarified that no actual explosives would be used, but added that the scheme would test the readiness and capability of the security guards to thwart potential bomb attacks.
Lacson earlier eyed the possible involvement of rightist elements in the recent bombings in Metro Manila, which resulted in the Rebolusyonaryong Alyansang Makabayan, founded by former Army colonel-turned-politician Sen. Gregorio "Gringo" Honasan, and the Young Officers' Union (YOU) feeling alluded to.
YOU leaders, in turn, claimed Lacson's men had a hand in the bomb attacks at SM Megamall and Glorietta.