Investigators said a 5-year-old girl's killer left his "calling card" Wednesday and warned that he intends to strike again.
An autopsy showed Samantha Runnion was sexually assaulted and suffocated before her nude body was dumped near a rural road, a cocky gesture the cops called the child killer's calling card.
Orange County Sheriff Mike Carona said Runnion was asphyxiated sometime Tuesday, though he didn't say how she was killed.
Autopsy results showed she was alive for hours after her abduction Monday evening. The sheriff also said Samantha may have fought against her killer and inflicted "injuries to his hands, arms and possibly face."
"Don't sleep, don't eat, because we're coming after you," Carona warned the killer in a televised news conference near the girl's home in Stanton.
Samantha's body was discovered Tuesday afternoon, less than 24 hours and about 50 miles from where she was abducted outside her apartment building. She was nabbed by a man who pulled up in a light green Honda or Acura car and asked for help finding his puppy. Samantha was playing with a 5-year-old friend at the time.
Authorities said there was no prime suspect, and Carona warned parents in the area to tell their children to stay away from strangers.
"We believe that he is a serial rapist and perhaps a serial killer and would strike again," the sheriff said.
Based on the playmate's account, police described Samantha's abductor as a Hispanic man with slicked-back black hair and a thin, black mustache. FBI agent Richard Garcia said the girl was able to identify speech patterns, leading investigators to believe the man is American rather than a foreigner.
News of the abduction spread fear in Stanton, a city of 38,000 southeast of Los Angeles.
Tammie Fike, 31, clutched the hand of her 6-year-old son, Anthony, as she headed to a memorial to say a prayer for Samantha. "I'm scared to let him go out," said Fike, who instructed her son to yell "fire" and to run if a stranger approached him.
"I'm only allowed to talk to friends of my mom," Anthony said.
Melissa Apodaca brought her three children to the memorial. She said she had made them watch newscasts about the abduction.
"They need to know this," she said.
Samantha's 27-year-old mother, Erin Runnion, who made an anguished plea for the return of her daughter a day earlier, remained in seclusion Wednesday.
The abduction was at least the third high-profile disappearance of a child in the United States this year. Seven-year-old Danielle van Dam of San Diego was found dead, and a neighbor is on trial. Fourteen-year-old Elizabeth Smart of Salt Lake City has been missing since June 5.
Two men who had gone out to do some hang-gliding spotted Samantha's body in a ravine near a glider launch site. It was in neighboring Riverside County near heavily traveled two-lane Highway 74, on the edge of the Cleveland National Forest.
"The way the body was found, the fact it was not buried, not hidden and such, and how it was left is almost like a calling card, like a challenge: 'I'm here and I'm coming back again.' This is the reason why we're saying this person is going to strike again," Garcia said.
The remains were identified by the girl's grandmother from photos.
"Because the body was found very quickly, we have a high expectation that there will be significant forensic evidence found at the scene and significant forensic evidence found on the body of Samantha Runnion," the sheriff said.
Samantha's mother, a British Petroleum analyst in Long Beach, and stepfather, Ken Donnelly, who works at an investment firm, were at work at the time of the kidnapping. Her grandmother, Virginia Runnion, was at home.
Samantha's father, Derek Jackson of Sunderland, Mass., was contacted by authorities and ruled out as a suspect, Erin Runnion said Tuesday.
The girl would have turned 6 on July 26. She was an advanced student who had just finished first grade at a private school.
Samantha's family said they moved from nearby Garden Grove to Stanton a year ago because they wanted a safer place for their three children where they could play outside without fear.
Brenda van Dam, whose daughter Danielle was abducted and killed in February, said she spoke with Samantha's mother to offer consolation.
"They were both sweet, wonderful girls who loved life and their family," van Dam said in a statement.
The Associated Press contributed to this report.