The Uber driver told cops Jennifer Espitia was sitting in the front and her husband was in the back seat shortly after midnight when they began arguing, according to probable cause documents.
The driver said Cameron Espitia swore repeatedly at his wife before the driver heard a boom and thought a tyre had burst, but quickly realised Jennifer Espitia had been shot, documents said.
The driver feared for his life and kept driving on Cameron Espitia's orders, police said.
Eventually, he told the driver to pull over. After the man left the vehicle, the driver called police.
The woman was shot in the head and died at a Seattle hospital, police said.
Police arrested Espitia nearby. Officers found a small pistol on Espitia in an ankle holster, police said.
Espitia also told police he didn't remember exactly what happened, that he woke up in the bushes and didn't know where he was, documents said. He later said he had a faint recollection of being in the vehicle.
Jennifer Espitia graduated from Mercer Island High School in Washington and was on the rowing team at Saint Mary's College in California, according to a college-athletics biography, The Seattle Times reported. She had won a community-service award for work as a peer educator at Planned Parenthood, working at a day care centre and building homes in Mexico.
Cameron Espitia worked for the US Coast Guard, court documents said.
- With AP