Jair Bolsonaro argued in court that a reaction to newly prescribed medications caused a moment of paranoia that made him believe his electronic ankle monitor was bugged.
Authorities had arrested him early Saturday after detecting interference with the device. Security officials feared he was preparing to flee into diplomatic protection to avoid imprisonment.
The former president has been under house arrest since August after being convicted for leading a failed coup. His transfer to prison was expected to take place soon.
Bolsonaro said that a painkiller and an antidepressant triggered hallucinations. Acting on what he described as a sudden loss of clarity, he used a tool to try to open the device.
Analysts cast doubt on his claim, noting inconsistencies with earlier statements. International responses were reserved, marking a shift in global political support.