The head of a government probe on the deaths of 104 aborigines in police custody has resigned, and indigenous activists Friday called the decision a devastating blow to the inquiry.

Prime Minister Bob Hawke said James Muirhead, federal court judge since 1977, resigned late Thursday to become administrator of the Northern Territory.Aboriginal groups called the decision a blow to their cause and expressed concern that the inquiry, set up in 1987 to investigate 44 aboriginal deaths in police custody since 1980, could be downgraded.

Since the inquiry began, the number of aboriginal deaths in police custody has grown to 104.