US police have found the decapitated and dismembered body of a woman inside two suitcases in a black BMW.

The remains of Sara Zghoul, 28, were discovered on Thursday after a call was made to Oregon police reporting a homicide.

Ms Zghoul, who worked as an actress, model and voice-over artist, was the mother of a young son.

A man, who has not been identified, was arrested later that night. He was found in a ravine and had suffered self-inflicted slash wounds to the throat and wrist, Oregon Live reported.

He and Ms Zghoul reportedly lived in the same town of Aloha, near Portland.

Michael Larsen told FOX 12 that he and his wife were sitting on their balcony when they saw the suspected killer, who was yelling for help in the bushland.

"It was really cold and rainy, and he's just sitting out there leaning against a tree," Larsen told FOX 12.

"The tone of his voice when he was yelling, it was very desperate."

It is not known if the pair knew each other and police said the suspect's identity would be released at later date.