Smith was wanted as a suspect in the death of her 2-year-old daughter, as well as for trying to murder her 13-year-old daughter, police chief Jason Schermerhorn said. Both girls were found at the Cannon Beach inn on Friday.
The Coast Guard spotted Smith on a logging road just hours after police issued a warrant for her arrest.
She will be formally charged with murder and attempted murder on Monday.
CANNON BEACH, Ore. - Police on Sunday said an arrest warrant has been issued for the mother of a 2-year-old girl found dead in a Cannon Beach hotel room on Friday.
Jessica Smith, 40, is wanted for aggravated murder and considered armed and dangerous, according to Cannon Beach Police Chief Jason Schermerhorn.
An autopsy on 2-year-old Isabella Smith was unable to conclude what caused her death, the chief said. Police are waiting for toxicology reports.
"It's hard to know with a child that size," said Schermerhorn. "They need to await a toxicology report."
Schermerhorn said Isabella Smith's manner of death was homicide. There were no signs of physical abuse, he said.
Isabella's sister, 13-year-old Alana Smith, was found seriously injured in the hotel room. Police said she was a victim of attempted homicide.
Alana Smith remains in protective custody at a Portland hospital, where she is recovering. She has been able to speak with her family, Schermerhorn said.
Authorities were called to the Surfsand Resort on Friday morning. The children were found by hotel staff.
Schermerhorn said the children's father, Greg Smith, is not a suspect and has cooperated with the investigation.
"There are no other suspects," he said.
Jessica Smith, of Goldendale, Wash., was driving a gold 2007 Chevy Suburban, according to police.
The FBI, U.S. Marshals and law enforcement agencies from other states are helping with the case, said the chief. The U.S. Coast Guard is providing air searches.
Schermerhorn said police do not know where Jessica Smith is. Anyone who sees Jessica Smith is asked to contact their local police. Detectives are working on tips as they come in.
"It's still wide open," the chief said. "Anything's possible. She could have gone to another state. That's why we're trying to get the information out."