The Department of National Parks, Wildlife and Plant Conservation chief Rutchada Suriyakul Na Ayutya was on Friday dismissed from the role.
Ministry of Natural Resources and Environment's permanent secretary Jatuporn Buruspat revealed that the dismissal paves the way for a transparent investigation into accusations against Mr Rutchada.
Mr Jatuporn said the ministry realised that a thorough investigation is likely to be a lengthy process due to a large number of people having been requested for testimony.
"What the ministry has done is based on civil service regulations. Mr Rutchada ceased to be a state official when the order was made on Feb 3. The investigation is to ensure transparency and fairness to all stakeholders. We want the public to be updated and regain trust in our organisation," he said.
Mr Jatuporn added that the committee would collect and assess any additional information and reach a consensus based on fairness.
Talerngsak Petchsuwan, the ministry's deputy permanent secretary who is heading the investigative committee, said 50 state officials had been questioned so far.
When this stage is completed, he will invite Mr Rutchada to hear the verdict.
Mr Rutchada can subsequently lodge an appeal with the Administrative Court if he so wishes.
He was arrested on Dec 27 at his office on suspicion of demanding or taking bribes from subordinates and malfeasance.
A total of 4.9 million baht in cash was found in his safe during the arrest, which was made following a tip-off from Chaiwat Limlikitaksorn, the department's director of the 9th regional conservative areas management office.
Names of forest officials appeared on envelopes stuffed with cash found in his office.
To boost public confidence in the department, Environment Minister Varawut Silpa-archa moved Mr Rutchada to an inactive post and appointed the chief of the Department of Marine and Coastal Resources, Attaporn Charoenchansa, as a stand-in.
Mr Attaporn immediately set up a full-scale inquiry and moved at least two other state officials to inactive posts following allegations of their involvement in the affair.