Family of Slain California Teen Norma Lopez Vows to Find Killer

(July 23) -- The sister of 17-year-old Norma Lopez, found dead in Moreno Valley, Calif., almost a week after she was reported missing, said this morning that she "will not rest until this murderer is found."

"I need to find the person that killed her and I want to know why. Why her?" Elizabeth Lopez, 18, said in an interview with NBC's "Today" Show.

Meanwhile, police are reminding parents that a killer is on the loose and to keep an eye on their children as the hunt continues.

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"We haven't caught the suspect who killed Norma," Sgt. Joseph Borja of the Riverside County Sheriff's office told reporters Thursday. "So obviously there is at least a murderer out there, so I would be vigilant, I would be aware if I was a parent. ... I would keep track of my children."

Lopez was reported missing when she didn't return from summer school July 15. Her badly decomposed body was found Tuesday, in a field between the high school and her home in Moreno Valley, according to The Associated Press. Investigators say there are signs that Norma fought back, but so far, there are no known suspects in the case.

One area resident says she sent her 17-year-old daughter to live with relatives until the killer is found. "It's scary," Sonia DeLeon told The Los Angeles Times. "The person is still out there. I work, my husband works; we can't keep an eye on her every minute.''

Elizabeth Lopez told the Los Angeles Times that her sister borrowed her shoes on the morning before she disappeared, and then made her a peanut butter and jelly sandwich in return, with a happy face made out of a banana on top.

"That's the last time I saw my sister," she said.

Borja said police are searching for the girl's killer.

"I believe this has been made personal because we all have children," he said, according to the AP. "It's probably our worst nightmare that our kids can just be taken from a street and killed."