Based on the STT information, the Finance Ministry has launched an investigation into official misconduct.
"Today we have sent an official letter to inform the Finance Ministry that we see signs of disciplinary misconduct," Saulius Urbanavičius, director of the law-enforcement body, told BNS.
He did not elaborate on what activities had aroused suspicion. The STT usually investigates corruption offenses.
The Finance Ministry said that Bradauskas is suspended from his duties for the period of the investigation.
"The State Tax Inspectorate is a key state institution. Therefore, the activities of the head of the institution cannot give rise to any doubt," Finance Minister Vilius Šapoka said in a press release.
Bradauskas, who has headed the tax authority since mid-April 2015, could not be reached by BNS for comment.
PM backs Šapoka's decision to investigate tax chief's activities
Lithuanian Prime Minister Saulius Skvernelis said on 4 January that he supported Finance Minister V. Šapoka's decision to investigate the activities of D. Bradauskas.
"The prime minister has been informed about the finance minister's decision regarding the VMI head and he supports the minister's position and his moves. Suspicions regarding the VMI head's activities must be investigated and the necessary decisions must be taken," Skvernelis' spokesman, Tomas Beržinskas, told BNS.
The STT usually investigates corruption offenses.