(CNN) -- Authorities believe that a registered sex offender who this month admitted killing two California teenagers attempted to follow an 11-year-old girl walking home from school the day before one of the teens disappeared, according to documents filed in the case.





John Albert Gardner, 31, pleaded guilty April 16 to killing Chelsea King, 17, and Amber Dubois, 14. He also pleaded guilty to a charge of assault with intent to commit rape in a December incident involving a third woman.





King was last seen leaving Poway High School in suburban San Diego, California, on February 25. Her car, with her cell phone inside, was found at Rancho Bernardo Community Park. King was known to run on the park's trails. Her disappearance triggered a massive search that ended a few days later, when King's remains were found in the park.





Dubois disappeared in February 2009 while walking to school in Escondido, California. She was considered a missing person for more than a year until her remains were found in March. Prosecutors said Gardner led police to Dubois' body after being assured that it would not be used against him in court.





Gardner avoided the death penalty with his guilty plea but will be sentenced June 1 to two consecutive life terms without the possibility of parole, under terms of the plea deal with prosecutors.





On February 24, a day before King went missing, an 11-year-old girl reported that she was walking home from school when she heard a vehicle slowly approaching her from behind, according to an affidavit requesting a police search of Gardner's home, posted on the website of CNN affiliate KTLA-TV. The documents were unsealed Monday, KTLA reported.





The girl told police the vehicle drove past her and then parked about 30 feet in front of her, the documents said. The driver stayed in the vehicle, the girl said, and did not attempt to speak to her. But a woman pulled up next to the girl and told her the person in the vehicle "seemed very suspicious" and offered to follow her home, according to the affidavit.





The man, who was in a black car, then made a U-turn and left, and the woman followed the girl the remaining two blocks to her house, the documents said. The girl's mother called police after her daughter told her what happened.





The girl's mother told authorities that after seeing a photo of Gardner following his arrest in the King case, her daughter said Gardner was "the guy in the car," the affidavit said. Gardner's girlfriend drives a black 2002 Nissan Sentra, according to the documents.





The documents also detail the December assault on the third woman near where King's car was found at the park. She told authorities she was on a hiking trail and a man walked past her, the affidavit said. She told him, "Good morning," and he returned the greeting, but then tackled her from the side as he passed her, knocking her to the ground on her back.





The man pinned her to the ground, and she screamed while struggling with him, the affidavit said. He told her to "shut up," and she said, "You're going to have to kill me."





"That can be arranged," he responded. The man then demanded money from her, the affidavit said.





She was able to sit up and used her elbow to strike him in the nose, telling police she felt "the crunch of cartilage." The man let go of her and grabbed his nose, she said, and she ran.





A woman also told police that she saw Gardner on the jogging trails near the park on the day King disappeared, the affidavit said. She said he was sitting and drinking a beer and had several empty beer cans around him. He warned her about a rattlesnake that was nearby, and they spoke briefly.





The woman said she ran past the man and then talked to him some more on her return trip. The man was wearing blue jeans and a Hard Rock Cafe T
Of what age was the girl that Gardner followed but scared off who was attacked who was scared off who killed 2 people Name the two girls that Gardner has admitted killing where was crime
11-year-old Chelsea King, John Albert Gardner, John Albert Gardner, Amber Dubois, San Diego,
question: Of what age was the girl that Gardner followed but scared off, answer: 11-year-old | question: who was attacked, answer: Chelsea King, | question: who was scared off, answer: John Albert Gardner, | question: who killed 2 people, answer: John Albert Gardner, | question: Name the two girls that Gardner has admitted killing, answer: Amber Dubois, | question: where was crime, answer: San Diego,