The manhunt follows the death of a man aged in his 30s on Saturday night.
He was found dead from a gunshot wound in a vehicle on Wayby Station Road.
Detective Inspector Scott Beard said the victim and the offender were known to each other and this was not being treated as a random attack.
"Police want to reassure the public that we have a team of dedicated staff working tirelessly on this case and our priority is locating Desmond Bourne as quickly as possible.
"We also want to acknowledge the members of the public who initially contacted Police on Saturday night, as well as over the weekend with information around sightings of the black Range Rover (registration KBK990) linked to this incident.
"We encourage anyone with information who is yet to contact Police to do so immediately."