Health regulators initially received a complaint about the online behaviour of Dr Christopher Kwan Chen Lee in 2016, but did not suspend the emergency doctor until more than two years later.

During that time Lee made dozens more disturbing posts online that were not considered as part of the investigation, including videos of pedestrians being killed in traffic accidents and images of dead bodies with terrible injuries, mostly of women. Lee was suspended from practising for six weeks from May as a result of the investigation.

On Wednesday, as a result of these additional posts uncovered by Guardian Australia, the Australian Health Practitioner Regulation Agency said the regulator was investigating Lee again.

Following a public outcry about the initial six-week suspension, Lee’s employer, Eastern Health, ordered Lee, 31, to step down from his position as an emergency doctor at Box Hill hospital in Victoria while the health district completed its own investigation.

A staff member of Ahpra, which regulates and investigates healthcare practitioners, confirmed that complaints about Lee were first made in 2016. “I can advise that we received the original complaint in December 2016,” an Ahpra spokeswoman said.

Those complaints related to comments Lee made online over just two days in which he said that some women deserved to be raped, along with other sexist and derogatory comments, while also posting proof of his name and identity as a doctor. In January 2017 Lee was notified that he was under investigation, but it took until April 2019 for the disciplinary action of a six-week suspension to be ordered.

While Ahpra investigators did uncover a few other posts made by Lee in addition to the original complaint, these were confined to four additional posts made by Lee on 3 January 2016, 3 December 2017, 9 January 2018 and 16 January 2018.

“There may have been others not uncovered during the investigation,” the Tasmanian Health Practitioners Tribunal chairman, Robert Webster, said in his judgment. “I do not think it could be said that the respondent’s conduct was isolated.”

Guardian Australia has uncovered dozens of other offensive posts made by Lee during the Ahpra investigation that were potentially in breach of the Medical Board of Australia’s social media policy. The health practitioner regulator, Ahpra, has previously said the policy makes it clear that a registered medical practitioner must act in the same way online as they do in person.

“The policy states that registered health practitioners should comply with confidentiality and privacy obligations, such as by not discussing patients or posting pictures of procedures, case studies, patients, or sensitive material which may enable patients to be identified without having obtained consent in appropriate situations,” a spokeswoman said.

Lee’s posts include sexually explicit photos of his wife. He added that if she ever divorced him, he would “slice her open from sternum to anus, rip out her entrails and bathe in her blood”. When asked if he was joking by a forum user, Lee replied: “Absolutely not. I would expect her to do the exact same thing to me if the situation was reversed.” These comments were made in 2018, after Lee was notified Ahpra was investigating.

Asked what he would do if he were to discover a cure for HIV, he responded that he would not distribute it to everyone because, for those who contracted the virus from sleeping with prostitutes or from injecting drugs, it was their “own fault”. In October, Lee was asked if his views had led to problems with his emergency department colleagues. “Yeah, there have been a few clashes with colleagues over the years,” Lee responded. In the same month, Lee admitted to mocking cancer patients.

Lee also posted his handwritten medical notes, including a photo of the gangrenous foot of a patient Lee he described as “thoroughly septic”, as well as details about that patient’s mental health, age and treatments.

He wrote that his online comments did not matter, because: “Aussies don’t care about what goes on in a separate forum in another country.” The online forum he posted on is hosted in Singapore.

A petition calling for Lee to lose his medical registration permanently has more than 3,000 signatures. Lee is not an Australian citizen, and is originally from Malaysia. He studied medicine at the University of Melbourne. Lee has said on forums that he is a permanent resident. A spokesperson from the Department of Home Affairs said it could not comment on his status or if the department was considering revoking it, due to privacy reasons.

In the meantime, the head of Melbourne Medical School, where Lee trained, sent an email to staff describing Lee’s comments as “repugnant and completely at odds with the values of this medical school”.

“This disturbing episode serves as a reminder that medical professionalism is a 24 hour-a-day way of living and that what you say or post on social media reflects the person that you are,” said the email, which was signed by course heads Prof John Prins and Prof Steve Trumble, and course director Dr Lisa Cheshire.

“If anyone is struggling to reconcile their personal views with what is acceptable for a medical professional, please make contact with a trusted mentor as soon as possible.”

A former colleague of Lee’s who used to work with him in the emergency department said Lee was sometimes in charge of the overnight shift at La Trobe regional hospital.

“He spent most of his night shifts wrapped in a warm blanket and posting in an online forum,” she said.

Many of Lee’s internet supporters have defended him online, describing his posts as “just trolling”.