Barbara Jean Davenport, 60, was taken into custody on Wednesday. She is the cousin of the veteran LAPD officer, and the murder victim's niece. Detectives say Davenport killed her aunt while attempting to rob her.
Investigators were able to connect Davenport through DNA from the crime scene.
"Miss Hughes was well respected in her neighborhood, she was well loved by her family. She certainly did not deserve to be murdered in the brutal fashion, and I am glad that we are able to bring some closure to this," said LAPD Police Chief Charlie Beck.
LAPD training officer Christopher Hughes found his 79-year-old mother, Cleo Hughes, dead in her home in the 1600 block of West 66th Street on June 3. At first, detectives were looking into whether she was targeted because of her son's job as an officer. She lived alone, and there was no sign of forced entry.
Police are still looking for the handgun that was involved in the shooting. Police did not say whether anyone else was involved in the crime, or what was stolen from the home.
Davenport is being held on $1 million bail.