The Los Angeles County Sheriff's Department confirmed the girl's identity as 9-year-old Trinity Love Jones, of Los Angeles County.
"Investigators have detained two persons of interest in this case and they are actively continuing their investigation," the sheriff's department wrote in a press release.
The identities of the two people have not been released.
The announcement came hours after a local family came forward identifying the girl. The sheriff's department said later Sunday night that the county medical examiner had confirmed that identity.
The family put up a makeshift memorial near where her body was found in a rollaway duffel bag in Hacienda Heights on March 5.
Antonio Jones, who said he is Trinity's father, described the girl as "fun, loving, big heart, bubbly."
"Little girl could've been whatever she wanted to be in life," he said.
The memorial at the site is adorned with balloons and teddy bears and declares "Rest In Heaven Our Trinity Love Jones."
Her body was found on a hiking trail south of Hacienda Boulevard and Glenmark Drive.
Officials said it appeared the body had been pushed off the edge of the roadway down an embankment onto an equestrian trail within 24 hours of the discovery by local workers doing maintenance on the trail.
She was pronounced dead at the scene, and the coroner's office later ruled her death a homicide. The exact cause of death is being withheld.
Anyone with information is asked to call the Los Angeles County Sheriff's Department Homicide Bureau at (323) 890-5500. Anonymous information can be provided through Crime Stoppers at (800) 222-TIPS.
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