Roach had walked around Central World and Petchburi Soi 15, 17 and 19, and the Thai police searched the 35 hotels and hostels in the area.
A man who is suspected to have robbed the Standard Chartered Bank branch on Thursday at Holland Village in Singapore was arrested in Bangkok on Sunday, with the help of the Royal Thai Police.
The Straits Times reported that Roach changed his room each night, starting with a four-bedder before switching to a six-bedder.
On Wednesday, Pol Col Nithithorn outlined how Thai police found Roach: They traced him through CCTV footage and the taxi driver who drove him from the airport.
Thai immigration police chief Nathatorn Prousoontorn said Mr Roach's right to stay in the Kingdom of Thailand was has been revoked under the Immigration Act and he would be sent to Singapore and put on Thailand's re-entry blacklist.
According to Channel News Asia, Roach has visited Thailand many times, but his trip to Singapore, where he made off with a bunch of cash, was the first.
Tourists bringing in more than US$20,000 (S$27,000) are required to make a declaration to Thai customs.
The reports said Roach would not speak to Thai police and had asked to speak with someone from the Canadian embassy.
However, it was not possible at the time as the embassy is closed on Sundays.
In a statement on their Facebook page, the police here said they managed to establish the identity of the suspect on the same day as the robbery, but the suspect had already left Singapore for Bangkok.
Singapore and Thailand do not have an extradition treaty but Singapore police have previously said both countries have strong bilateral ties and are in talks to see whether the suspect can be released into Singapore's custody.
It is unclear if the embassy ever got in touch with him.
According to documents seen by Shin Min, Roach was born in Sydney in 1989 but now holds Canadian citizenship.
Thailand's national police chief Jakthip Chaijinda (C) speaks during a news conference on the bank robbery in Singapore at the Immigration Detention Center in Bangkok, Thailand, July 13, 2016.