Bangkok ? Up to 75 percent of the security cameras were broken along the getaway path taken by the main suspect in last week’s deadly Bangkok bombing, Thailand’s police chief said Monday, revealing a major obstacle to an investigation that has only fuzzy images of the still-unidentified man.

Investigators are trying to “put pieces of the puzzle together” but have had to use their imagination to fill holes left by cameras that failed to record his movements, said national police chief Somyot Poompanmoung, openly frustrated as he spoke to reporters one week after the blast.

“For example, the perpetrator was driving away ? escaping ? and there are CCTV cameras following him. Sometimes there were 20 cameras on the street but only five worked,” Somyot said. “Fifteen were broken, for whatever reason, they didn’t work.”

“The footage jumps around from one camera to another, and for the missing parts police have had to use their imagination,” he said. “We’ve had to waste time connecting the dots.”

Another challenge is that investigators lack sophisticated equipment like police use on the popular TV crime series “CSI” to render blurry video clear, he said.

“Have you seen ‘CSI’?” Somyot asked reporters. “We don’t have those things.”

One week after last Monday’s bombing at the capital’s revered Erawan Shrine, which left 20 people dead and more than 120 injured, police appeared no closer to tracking down suspects or determining a motive for the attack.