The operation was part of an investigation into the suspect behind the Sathorn pier bomb. The suspect, who wore a blue shirt, was caught on CCTV carrying a bag and leaving it on Taksin Bridge before kicking it into a canal on August 17. It exploded the following afternoon without causing any casualties.
In yesterday's joint operation, luggage and a computer were seized and fingerprints and DNA evidence collected to check for links to the Erawan Shrine and Sathorn bombings.
An informed source said that two female students rented the room before the mother of one of the students arranged for a middle-aged woman to stay with them two months ago.
The source said that a police probe found that three men, who were believed to have fled the country, had left items at the apartment.
An initial search of the apartment did not uncover any bomb components or substances used in bombs, the source added.
Sriwara said the search stemmed from information that an individual involved in the bombings had left personal items at the apartment a few days ago.
The authorities wanted to get details on that individual and possibly come up with a sketch of the person after speaking with the three women, he said.
"We cannot confirm if the person that left the items was among those wanted in this case. We can just say it wasn't Wanna Suansan," he said, in reference to the Thai woman wanted in connection with the case.
Another informed source said that initial inquiries found that the mother's friend who resided at the apartment might be linked to the man in a blue shirt who carried the Sathorn Pier bomb. It is thought she may have arranged a taxi to get him to the pier.
She is also believed to be the person who collected personal items of another suspect in the case at an apartment located between Soi On Nut 44 and 46 police searched on Saturday night.