Unbeknown to his pupils, father-of-two Macphallen Kuwale had a secret narcotics factory in his home in Cardiff.
In it was more than 100 grammes of cocaine, £900,000 worth of cutting agents and a pressing machine to make Class A substances appear of a higher grade.
Detectives' investigations also uncovered further evidence similar to hit drama Breaking Bad, which tells the story of chemistry teacher Walter White who produces and sells methamphetamine in the wake of serious health and money troubles.
In a bid to cover his tracks, White, played by actor Bryan Cranston, assumes the alias of Heisenberg and has a secret second mobile phone.
Welsh detectives investigating Kuwale found that he had arranged drug deals via "coded" text messages under the guise of "Mac".
He was handed a three-and-a-half year jail term by Cardiff Crown Court last year before The General Teaching Council Wales (GTCW) conducted a disciplinary hearing in the Welsh capital today.
Detective Timothy Jones, of South Wales Police's drug squad, told the GTCW panel that 111 grammes of cocaine was seized during the raid at Kuwale's home in Llanrumney, Cardiff, in December 2012.
He said: "Kuwale was heavily involved in the supply of cocaine.
"He was involved in street level dealing as well as a sophisticated wholesale operation.
"It was totally unusual. It is not something that you come across every day."
After being arrested, Kuwale had claimed he had been severely stressed at the time amid money problems which nearly resulted in his home being repossessed.
However, technology whizz Kuwale - who holds a degree in computing - flatly denied being a drug dealer and insisted he was only holding the drugs as a favour for someone.
Mr Jones, who has worked on hundreds of narcotics cases during his 11-year police career, said that, in his experience, people in the drugs world "did not do favours" for nothing.
He added: "This was in the higher echelons."
Also giving evidence at the GTCW hearing was Kuwale's former headteacher Andrew Warren.
He contradicted suggestions the registrant had been treated unfairly while at the school.
Mr Warren said the school continually tried to help Kuwale after concerns about his teaching standards were raised by parents and pupils - some of whom complained about their teacher's poor level of English.
GTCW panel chairman Steve Powell said the body had no option but to permanently ban Kuwale from teaching.
He said: "Mr Kuwale presents a significant and ongoing risk to the standards of the profession.
"His involvement in the illegal drugs trade is evidence of deep-seated attitudinal problems.
"We cannot be satisfied that there is no risk of repetition.
"The proportionate sanction is an indefinite prohibition order.
"The wellbeing of pupils must be protected and the reputation of the profession maintained."
Kuwale, who had asked for the hearing to take place in private, has 28 days to appeal against the GTCW's decision.