Lt. Gen. Prawut Thavornsiri

Authorities will seek an arrest warrant soon for a man who shared an apartment with a suspect who was arrested a week ago when a police raid found bomb-making materials in his room, said national police spokesman Lt. Gen. Prawut Thavornsiri, adding that the man's nationality was unknown.

The arrested man, whom Thai authorities have identified as Adem Karadak, was brought to court Saturday to obtain permission for his detention to be extended. 

National police spokesman Lt. Gen. Prawut Thavornsiri said the two men "were most likely not involved."

The two men were seen in a security video standing in front of the prime suspect as he removed a backpack and placed it on a bench at the crowded shrine shortly before the blast, and police had believed they were accomplices.

"The yellow shirt guy is not just the suspect. He is the bomber," police spokesman Lt. Gen. Prawut Thavornsiri told The Associated Press.

Prawut earlier released several photos of the man, with and without the backpack, on social media. 

The images were apparently taken from closed-circuit video at the Erawan Shrine on Monday evening before the bomb exploded. He confirmed that the man is suspected in the bombing when contacted by The Associated Press.