Authorities probing the mysterious murder of a 13-year-old California girl took DNA swabs from students at her former school in their hunt for the child's killer.

The body of Jessica Funk-Haslam was found in the dugout of a baseball field at Rosemont Park in Sacramento County on March 6. A coroner ruled that the eighth-grade girl was hit in the head, stabbed and asphyxiated.

Fox affiliate KTXL-TV reported Monday that detectives visited Albert Einstein Middle School to question three or four students and take DNA cheek swabs from them.

"My child's in a room with two detectives being questioned and grilled and I’m sure he was quite frightened, which is very upsetting," Michaela Brown, the mother of one of the students, told the station.

The crime has so far baffled investigators, who say they believe the girl spent several hours in the park with someone she knew before being killed.

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Authorities announced last month that they were reviewing a grainy surveillance video showing an unidentified male running from the park at about the time the girl was killed.

The video reportedly showed the suspicious individual ducking into a side street when a car approaches and then reemerging after the vehicle passes him. 

It's not known whether police have since identified the person in the video and whether he has been ruled out in the investigation.  

The girl's mother has said she left the family's home without permission, saying she was planning to meet someone but did not say whom.

A $10,000 reward is being offered for any information leading to the person responsible for the girl's death. 

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