Authorities who have spent the past three weeks searching in the mountains of Washington state for an ex-soldier wanted in the deaths of his three young daughters say there is no evidence that he remains in the area or that he is alive at all.

The search for Travis Decker, the father accused of killing his three young daughters, has shifted as the manhunt entered its fourth week, authorities said.

See new images from the U.S. Marshals Service showcasing the challenging search for Travis Decker, accused of murdering his daughters, as the manhunt continues in the Washington wilderness.