Los Angeles authorities are investigating more than 600 tips after announcing a $1 million reward Sunday for information leading to the arrest of a fugitive ex-cop wanted in the murders of three people.

The trail for 33-year-old Christopher Dorner went cold Thursday after authorities found Dorner's burned-out pickup truck near the ski resort town of Big Bear in the San Bernardino Mountains. Police have since said they discovered weapons and camping gear inside the vehicle.

The search scaled down as the weekend went on, but a helicopter with heat-seeking technology scanned the area as two-dozen officers went back to some of the 600 cabins they earlier visited door to door.