The documents also said two female joggers were convinced they had encountered Gardner on the afternoon of Feb. 25, the day he attacked and killed King when she went for a run in the park.
One woman said she was convinced a man she briefly spoke with about coyotes and snakes was Gardner.
Investigators linked Gardner to King's murder through semen found on her underwear, according to the search warrants unsealed in response to a request by The Associated Press and other news organizations.
King's body was discovered in a shallow lakeside grave five days after she vanished.
The search warrants said the 11-year-old girl told San Diego police on Feb. 24 that a man in a black car slowly drove by and parked as she walked home alone from school in the Rancho Bernardo area. The driver made no effort to speak with her.
A woman then pulled up beside the girl, told her the man looked suspicious, and offered to follow her two blocks to her house. The man then made a U-turn and drove away.
The girl told a family member the man had stared at her before pulling forward, and that she later recognized Gardner from a photo published after his arrest in the death of King.
The warrants said authorities seized 11 shovels, three pickaxes and other digging tools from Gardner's home in Lake Elsinore along with a "Hard Rock Cafe Baghdad" T-shirt and other clothing.
They also found a tool case with black electrical and duct tape in a storage unit in suburban Escondido; black duct tape and a fast-food receipt from Feb. 25 in his girlfriend's car; and several "Hard Rock Cafe" shirts and a shovel at his mother's home in San Diego.
Gardner, 31, pleaded guilty April 16 to raping and murdering King and 14-year-old Amber Dubois, who was abducted while walking to school in Escondido in February 2009.
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