A diver edges into the Red River through an opening cut through the ice on Jan 3. ((Sheila North-Wilson/CBC))

Police divers ended their search Sunday for the body of six-year-old Nathaniel Thorassie in Winnipeg's Red River.

The search was called off when the ice conditions were deemed too treacherous.

The head of the dive team, consisting of members from the Winnipeg Police Service, the Winnipeg Fire Department and the Canadian Amphibious Search Team, told CBC News the search for the boy ended Sunday at sundown with no success.

Sgt. Rob Riffel said that coming up empty-handed is a huge disappointment to the dive team members.

His unit and volunteer divers from the Canadian Amphibious Search Team (CAST) searched the murky bottom of the river for 28 days, covering more than a kilometre but Thorassie's body was simply not to be found.

The Manitoba Search and Rescue Association (MSRA) also scoured the river at one point, picking up the effort after the Winnipeg police dive unit briefly halted its search in mid-December.

Thorassie was playing on the ice and fell into the river on Dec. 4. Police and volunteer divers have been battling water conditions and zero-visibility in their search for the boy's body.

Mclain Flett, the boy's mother, said she was upset the search has ended and still believes that her son's body could be found.