Try to check if there are CCTV in that area, the city government already installed a number of CCTV in vital areas like Colon St., so that it can record anything that can be used to solve a case. And how about the cab? What taxi company is it? Body number? This small things can solve cases like these. Any witness during that time?
Try to go to the NBI office, they can set-up a fake post of an expensive item, maybe that girl will contact you again, this time it will be an entrapment operation.
And that girl? Dapat madakpan na siya bago siya mabaril ng kanyang mga biktima.