SAN DIEGO -- A missing Temecula teenager who was last seen in Mira Mesa may have vital information about the death of her best friend -- or she may herself be a victim, 10News reported.

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Hear From Heather's Parents

Heather Steimer, 18, (pictured, left), has been missing since July 21 and was last seen at a gas station in Mira Mesa.

The search for Steimer took on new urgency when the body of her best friend, Jennifer Ross, was discovered in an Escondido flood channel.

Ross' boyfriend, Bennette Douglas, has been arrested in connection with her death, according to 10News.

Her parents are fearing there is a connection between their daughter's disappearance and her best friend's death.

"It's the worst thing a parent could go through, is the not knowing," Heather's mother, Lillian Scott, said.

Scott said the family's top priority is showing Heather's picture to the public. The family has distributed 1,500 fliers with Heather's picture.

"One minute we're positive, and the next minute, we think the worst," Scott said.

Anyone with information should call Escondido police at (760) 839-4722.