A Mexican national accused of bludgeoning and stabbing a woman to death along Interstate 90 during a drug-fueled rage in March pleaded guilty Tuesday to murder in Adams County Superior Court.

Manuel Argomaniz Camargo agreed to a plea bargain in the March 1 slaying of his girlfriend, Ana Montelongo Garcia, while they were driving from Chicago to Moses Lake with their 3-year-old son. Argomaniz left Garcia’s nearly naked body near their vehicle along the side of I-90 near the Odessa exit.

In a news release, Attorney General Bob Ferguson said the plea bargain holds Argomaniz accountable and spares the family the ordeal of a trial. The state will recommend he serve nearly 30 years.

Argomaniz told investigators he had been snorting cocaine and meth to stay awake on the long, cross-country drive and became convinced Garcia was a witch who was casting spells to make the car malfunction.

A recent story in The Spokesman-Review revealed Argomaniz lived in the United States illegally for at least four years and twice avoided deportation after arrests by the Washington State Patrol and Border Patrol. An immigration judge in Chicago reportedly allowed him to stay in the United States to keep the family together.

The couple weren’t married, but she was a legal resident and the child was born in the United States. At the time of the killing, he reportedly was taking Garcia and the child to Moses Lake to live with her mother so he could leave them.