Updated

Authorities have given up the search for three women they believe were killed in Southern California by a pair of convicted sex offenders who were wearing GPS trackers, police said Friday.

Too much time has passed since the women vanished and it would be difficult to search and possibly close for months several landfills where they may have been buried, Anaheim police Lt. Bob Dunn said. "Very seldom do searches of these landfills after that time period produce the actual victims."

"All of those factors made it challenging," Dunn told the Los Angeles Times (http://lat.ms/1kriQO3 ).

Franc Cano and Steven Dean Gordon are charged with raping and killing Kianna Jackson, Josephine Vargas and Martha Anaya in Orange County last fall while the men were out on probation and wearing monitors as registered sex offenders.

The men's evasion of their electronic supervision has drawn outrage from victims' families and public officials.

The two are also are charged with the death of Jarrae Estepp, whose body was found in a trash-sorting plant.

Anaya's relatives held a brief memorial for her Friday at one of the landfills where police believe her body might be.

"I never thought I'd have to say goodbye to a loved one at a landfill, much less my own child," said Anaya's mother, Linda Salcedo.

Salcedo said she would continue handing out fliers and seek out people who may have information so she can learn exactly what happened to her daughter.

"I understand, they've said we cannot keep looking for them," Salcedo said. "But as a mother, I will keep searching."