Authorities hadn't "seen anything like this for at least a couple of years meaning that no one has dared to spray paint graffiti on this particular wall or any other in the surrounding area", Lefevre said.
"They admitted to the crime", Pol Maj Anon Cherdchutrakulthong told Reuters.
At the time of their arrests, the graffiti had already been scrubbed off by city workers.
"Britney is a very likeable person" and called her "very strong", she added.
Canadian Brittney Lorretta Katherine Schneider, left, and British Furlong Lee, second left, stand in front of Tha Pae Gate in Chiang Mai province, northern Bangkok, Thailand.
"You would have to know Britteny to know this is not her", said Schneider.
If found guilty, the tourists could each face 10 years behind bars and a 1 million baht fine, which equals around $40,000.