Julio Rocha was located in Mexico and booked at the West Valley Detention Center Wednesday night, according to Chino police.
Rocha was being sought for the murder of Thalia Flores and attempted murder of a male victim on March 21.
Family members said Flores was gunned down in her car after leaving work. Her wounded male passenger was able to walk to a hospital with his injuries.
The victim's sister said Rocha and Flores were high school sweethearts, but a month ago, her sister left the abusive relationship.
A co-worker who asked not be identified said on more than one occasion, Rocha stalked Flores while she was at work.