
Pol LtColonel Thawornwut Sriphruek identified the two suspects as Wanphen Duangmanee, 43, and Thanaphol Rermjam, 29.
Investigators are interviewing more witnesses to secure a warrant for another unidentified woman.
Thawornwut said the two known suspects regularly used a green car with licence plate number Phor Samphao Ngor Ngoo 7104 Bangkok.
Anyone spotting them is urged to call Hang Dong Police Station in Chiang Mai at (053) 441 8013.
A cosmetic surgeon said collagen, which was injected into Phannee Nongpingkham by the three suspects at their Chiang Mai clinic before the woman died a few hours later, was not suitable for breast enlargement.
Associate Professor Aphirak Chuangsuwanich of Chulalongkorn University said collagen could cause allergies and did not have lasting effects.
Collagen, extracted from cow protein, is better for smoothing or filling in wrinkles around the eyes or the nose.
Collagen must also be applied only by surgeons or certified dermatologists and even then can cause blindness when used near the eyes, as it may be accidentally introduced into blood vessels, the doctor added.
The Nation