DNA evidence found on the body of 5-year-old Samantha Runnion matches the man arrested in her killing, sources confirmed.

Jim Amormino, a spokesman for the Orange County Sheriff's Department, would not confirm or deny the report, but said authorities have evidence linking Alejandro Avila, who was arrested Friday, to the crime.

"We are 100 percent sure we have the right man based on circumstantial, physical and forensic evidence," Amormino said.

Avila, a production supervisor, has denied involvement in Samantha's abduction and killing and claims he was at a shopping mall at the time. Avila's sister, Elvira, told the Orange County Register that he missed a family dinner that night. Elvira also said Avila told his family that investigators found fibers under Samantha's fingernails.

Investigators took clothing from Avila's apartment for testing.

In an interview with the Times before his arrest, Avila said detectives took a sample of his blood and photographed a scratch on his leg.

Authorities have said they believe the girl struggled with her killer, who was once acquitted of child molestation charges.

Meanwhile, mourners from throughout Southern California have been flocking to the little girl's home to express relief and gratitude that an arrest has been made.

"It happened to everybody," area resident Lisa Eaddy said as she joined people lining up to spell out Samantha's name with candlelight Friday night.

"The mother said Samantha would have loved to see her name in lights," said Rebecca Clifford, who lives in the same Los Angeles suburban townhouse complex where Samantha was abducted.

Mourners have been contributing flowers, stuffed animals and other keepsakes to a huge memorial in the complex's courtyard. Many children wrote poems and letters in tribute to Samantha.

"It's overwhelming," said Roland Adkins, who lives in the complex and helped organize the memorial. "People are touched. If you're not touched by this story, you can't be touched."

The Associated Press contributed to this report.