When issues regarding his APC came to light, Pathlab made further inquiries, which found Mr Laverty had also been working illegally in New Zealand - at which point he was sacked.
He was arrested and deported to Thailand in October last year, she said. It was not known where Mr Laverty was now.
While Mr Laverty was working at the labs, his responsibilities included processing and interpreting specimens, testing pathogenic micro-organisms and interpreting stained slides.
While at Pathlab, he was promoted to senior scientist, overseeing the molecular work in the microbiology department.
TLab manager Dean MacFarlane told the tribunal he trusted Mr Laverty.
"I had no reason to doubt him about these matters and made no further inquiries about them other than to confirm that he was registered with the Medical Sciences Council of New Zealand."
That practice had since changed and was more robust, he said.
Pathlab Microbiology head Murray Robinson said when it was discovered the lab had not reimbursed Mr Laverty for costs in keeping his APC up to date and he in fact had no current APC, Mr Laverty was put on administration duties.
Mr Laverty was issued with an interim practising certificate while an investigation by the PCC was undertaken.
Mr Robinson said he never had any concerns about the quality of Mr Laverty's work.
"I and Pathlab am most concerned about the apparent level of dishonesty and deceit by Mr Laverty in his dealings with us in relation to his APC status in 2013."
Medical Sciences Council registrar Mary Doyle told the tribunal an interim practising certificate would never have been issued if it was known he did not have a valid working visa.
As Mr Laverty's whereabouts in the world was not known, she said it was not known if he would pay any costs towards any costs the council had incurred.
The tribunal said the PCC had proved its allegation.
Tribunal Wellington deputy chairman Ken Johnston said Mr Laverty's actions compromised the integrity of the two labs and the integrity of those who worked there.
The tribunal reserved its decision on a penalty.
Outside the hearing Mr Robinson said the company had reviewed Mr Laverty's work after it was realised there was no valid APC.
He said there were no issues around the quality of the work.
Mr MacFarlane said given the length of time that had passed, it was "impossible" to review Mr Laverty's work, but he had passed competency reviews during his employment at TLab.