(CNN) -- Investigators searched Monday for a California teen, a police spokeswoman said, a day after authorities arrested a man suspected of rape and murder in connection with her disappearance.
Police have been searching for Chelsea King, 17, since Thursday, said Susan Plese, a San Diego County Sheriff's Department spokeswoman.
The last reported sighting of the high school senior was at school, Plese said. Her car, with her cell phone inside, was found parked at Rancho Bernardo Community Park. King is a cross-country runner who often goes to the park to run on its many trails, Plese said.
Jan Caldwell, a spokeswoman for the sheriff's department, said Monday that investigators are using a variety of specialized resources, including search dogs, in combing 14 miles of the Lake Hodges shoreline, located inside the park.
Sheriff William Gore told reporters Sunday that authorities were hoping to find King alive.
Caldwell reiterated that point Monday, saying "We're going to work as hard as we possibly can as long as we need to."
Police arrested John Albert Gardner III, 30, Sunday afternoon after evidence pointed to him as "possibly involved" in King's disappearance, Gore said. He did not say what kind of physical evidence detectives uncovered. He is being held in the San Diego Central Jail on suspicion of rape and murder, according to jail records available online.
Gardner will be arraigned Wednesday, said Steve Walker, a San Diego County district attorney's spokesman. There has been no decision on what formal charges Gardner will face, he said.
Gardner is a registered sex offender in California. The registry lists his offense as "lewd or lascivious acts with child under 14 years."
Homicide investigators questioned Gardner after his arrest, Gore said. An interview by homicide detectives is the "normal protocol in cases such as this," he said.
Police are looking into whether Gardner is connected to an attack on a jogger in the park several weeks ago, Capt. Lisa Miller said.
"I want to emphasize, this investigation is not over," Gore said. "Our primary goal has been to find Chelsea King."
Thousands of San Diego's residents have come out to distribute fliers that seek help finding King, Plese said. Police have made several searches in the county for her, Gore said. The 38-acre park is also still being searched.
King's mother, Kelly King, expressed gratitude to community members for their efforts.
"My heart is overflowing with all the support and all this love, and there's no words for it," she said, according to CNN affiliate KFMB.
Anyone with information is asked to call police at 858-565-5200.
CNN's Khadijah Rentas contributed to this report.