Philip Patrick Policarpio was captured by agents with the U.S. Customs Border Protection on Sunday, the FBI said.
The 39-year-old was taken into custody at the San Ysidro Port of Entry as he was crossing into the United States from Tijuana.
Authorities said on April 12, Policarpio and his girlfriend, 32 year-old Lauren Olguin, were visiting a friend's home in the Rampart area when he suddenly became angry with her. Police said he began punching her in the face then pulled out a handgun and shot her in the forehead.
He was on parole for a 2001 assault conviction when the murder happened.
On April 19, the Los Angeles Police Department issued a warrant for his arrest and he was charged with murder by the Los Angeles District Attorney's Office.
Policarpio was added to the FBI's "Ten Most Wanted Fugitives" list earlier in May.