An Ottawa police source said police have "reason to believe" a man's body, which police divers continue to search for, belongs to 23-year-old Sultan of Calgary.
He is wanted for second-degree murder in connection with the shooting of 18-year-old Cook.
Cook was shot dead while trying to track down his lost cellphone on June 14 in London. His funeral was on Monday.
Ottawa police say a man allegedly struck two bike-riding police officers with his car on Wednesday afternoon in Ottawa's Lowertown neighbourhood.
Police said he then tried to swim across the Rideau River and ran into trouble in the water, so two officers jumped in the river to try to rescue him. He then slipped under the water, police said.
The Ottawa police major crimes unit said it started investigating the case overnight.
London police are also looking for a second suspect in Cook's death. He is described as a black male with very short hair. He was last seen wearing a black jacket or shirt and a fitted cap.
A third man, who got out of the vehicle just before the shooting, is being asked to contact police and identify himself.