|Alias|| The Vinegar Hill Slayer|
Numerous unspecified others
|Country of Origin|| U.S.|
|Family|| Unnamed father (deceased)|
Helen Chou (mother)
Natalie Huang (sister; deceased)
|Pathology|| Serial Killer (originally)|
Spree Killer (later)
Lonely Hearts Killer
|Signature||Leaving purple orchids on victims' bodies post-mortem|
|Victims|| 14 killed|
|Status||Deceased (shot by Seger)|
|Portrayed By||Ivan Shaw|
|First Appearance||Type A|
"It's not your fault, it's how you were raised."
Michael's father died at some point while he and his younger sister Natalie were young, leaving them to be raised by their mother Helen. Due to Helen being busy with her job as a corporate executive, Michael and Natalie would be left alone at home most of the time. Michael would later make allegations of abuse and neglect against his mother, though these claims would be investigated and declared unfounded by Social Services. For unknown reasons, in 2001, he raped Natalie, presumably feeling guilty afterwards and repressing the memory of ever doing so. When Helen found out about this, she went to live with Natalie in Taipei, Taiwan while Michael stayed at a boarding school in the U.S. Presumably as a result of being raped by her brother, Natalie later committed suicide by stabbing herself in the heart with her favorite flower, a purple orchid, in her lap.
When Michael found out about this, he snapped, convincing himself that Natalie's death was the result of his mother's supposed neglect, and started serial killing in 2001, murdering four women, each of them resembling his mother, in a six-month span and staging each of their bodies based on how Natalie took her own life. The murders would cause him to be dubbed "The Vinegar Hill Slayer" by the media because of the neighborhood he was active in. One of the women he killed was Lisa Sojourn, a translator for the United Nations and a close friend of both Emily Prentiss and Clara Seger. Eventually, the New York Police Department requested assistance from the BAU, but the investigation into Michael's murders was put on hold when the Bureau's top priority switched to terrorism following the 9/11 terrorist attacks. Following the Vinegar Hill murders, he traveled to seven Polynesian countries using different aliases and killed a woman in each of them. At some point after reaching his final destination, Taipei, he acquired a silicon sex doll and imagined it was Natalie, having been unable to cope with his sister's death.
Michael targeted women aged in their thirties who worked professional jobs, were divorced, had children, and physically resembled his mother in 2001, each of them acting as surrogates for her. With his Taiwan murders, he would find his victims on dating websites using a fake profile and charm them into going on a date with him. It is unknown how he found his victims in the other countries he killed in, although it is assumed he found his victims in a similar manner.
After his victims talked about their jobs and their children during their dates, he would give them drinks that he laced with Midazolam beforehand, to sedate them, and then put them in the trunk of his car once they started to fall unconscious. Right before they fell unconscious, Michael would say "It's not your fault. It's how you were raised." to them. His signature was stabbing his victims in the heart and leaving a purple orchid on their laps, as a reference to his sister's suicide. With Yu-Ting Meng, he killed her by stabbing her in the heart and did not go on a date with her or drug her. This was because he was nearly caught by the IRT and the Taipei police after drugging one of his would-be victims.
The initial profile of Michael complied by the BAU in 2001 said that he was aged in his late teens to early twenties and a native of New York who was sophisticated, but had anger issues towards women.
The premise of a serial killer with double nationality beginning his spree in the U.S. and continuing it in his other home country may have been based on a theory about the unidentified New Bedford Highway Killer, which proposed that he was a Portuguese national who then went on to commit the Lisbon Ripper murders and possibly other crimes in Europe. In both cases, the possibility was raised first by the other country's law enforcement officials, and the FBI sent a team overseas to investigate.
- Unspecified date, New York City, New York, U.S.: Natalie Huang (his sister; raped only)
- Pre-September 2001, New York City, New York, U.S.:
- Lisa Sojourn
- Three unnamed women
- Unspecified dates from 2001 to 2017:
- Unspecified locations: Three unnamed women
- Vanuatu: Unnamed victim
- Kiribati: Unnamed victim
- Solomon Islands: Unnamed victim
- Niue: Unnamed victim
- 2017, Taipei, Taiwan:
- Lynn Zhou
- Mary Gau (intended)
- Yian Chen
- Sara Yee (drugged and intended to kill, but abandoned the plan when the IRT arrived)
- Yu-Ting Meng (fatally stabbed in the heart; wasn't drugged)
- Helen Chou (his mother; attempted)
- Michael is the first unsub whose identity is revealed to the audience in the beginning. His case is also the first in the series in which the team knowingly departs to investigate the murder of a foreigner by an American overseas, rather than the opposite.