The Ethical Standards Command is investigating the death of a man in Cairns this morning.
Initial information indicates a 36-year-old man presented to the front counter of the Cairns Police Station in relation to an unrelated matter at 5.30pm on Sunday.
He was taken into police custody on an outstanding arrest warrant and transported to the Cairns Watch house.
Just before midnight the man was observed acting in an unusual manner, when he suddenly collapsed. Medical treatment was provided and he was taken to the Cairns Base Hospital, but died sometime later.
Police will prepare a report for the Coroner, and the CMC has been advised.