Launching an open investigation, the Yangpyeong Police Station asked for tips and/or cooperation from citizens to nail the suspect, offering a reward of 3 million won ($2,400) in cash.
So far, police have conducted a low-key investigation into the incident that took place on Aug. 5. However, they recently decided to change their method as little progress had been made.
The police showed new surveillance camera images of the suspect caught on Aug. 2 in which a man seemingly aged between his late 30s and early 50s is strolling around the tomb for about 13 minutes, measuring length and writing something.
In previously released images last week, a man, who police presume is the same individual, approached Choi's tomb, made a hole in it with a hammer, and took the urn, at 3:45 a.m.
"Though blurry, we can identify the appearance of the suspect through the new images because he was exposed to light," Woo Jae-jin, the chief investigator, said. Based on the first images, police believe a mentally challenged person or those believing in shamanism is involved in the crime.
Woo said the police are not ruling out the possibility that the criminal is an ordinary person with no criminal record.
The investigator added it must be a premeditated crime as the suspect cleaned up the scene after stealing the urn.
The National Scientific, Criminal and Investigation Laboratory inspected the scene in search of fingerprints and possible DNA traces on liquor bottles left at the scene, but found nothing. Surveillance videotapes of nearby highways are being studied to check traffic to the facility, the police said.
The mother of the late actress urged the criminal to return the urn. "Can't you let the poor thing rest in peace," she said. "My heart is torn into a thousand pieces."
Choi, who enjoyed a 20-year acting career, committed suicide last October at her home in Seoul, allegedly from depression following rumors that she had lent money to the late actor Ahn Jae-hwan, who killed himself a month earlier in the face of snowballing debt.