Authorities are investigating the killing of a woman found dead in her apartment in Washington state and graphic photos online that purport to show her body.

The images were posted before authorities learned of the death on Tuesday in Port Orchard, a city west of Seattle, police said. The death appears to be a homicide, sheriff’s deputy Scott Wilson said.

Wilson said the photos appeared to have been posted anonymously on an image-sharing website just before 3pm on Tuesday, about a half-hour before the death was reported, the Kitsap Sun reported.

The photos included text indicating that law enforcement would know about the death once one of the woman’s relatives found her body. A relative did find and report the body, Wilson said, but he would not release that family member’s relationship to the woman.

He said the sheriff’s office was taking the photos seriously but was “unable to confirm whether those photographs are of this victim”.

Authorities have not identified the woman. They said they do not believe the attack was random, and they were trying to locate the woman’s missing car.