On the night of Nov. 15, 1998, Melinda Brown said goodbye to her parents around 7 p.m. and set off to a house party in Simi Valley, Calif.

Later that night, around 10:30 p.m., local police broke up the party because of neighborhood complaints about the noise. Brown, 18, and a group of friends ended up at an apartment complex close to where the original party was located.

“It was a smaller gathering,” Ventura County Sheriff’s Office Sgt. Craig Hennes tells PEOPLE. “They continued to party for a few more hours there.”

Brown never returned home that night. And when she didn’t show up to her shift at In-N-Out Burger two days later on Nov. 17, a missing person report was filed.

Her remains were found 10 days after that next to a shallow grave a couple hundred yards off a popular dirt road in the Hungry Valley area of Los Padres National Forest near Gorman.

“There was a lot of animal activity,” says Hennes. “It looked like some of the wildlife had unearthed her and dragged her out of the shallow grave.”

She had been shot in the back, he says.

Missing Person Melinda Brown.courtesy of the Ventura County Sheriff’s Office

Brown’s last movements have puzzled Ventura County detectives for the last 27 years.

Witnesses allegedly told investigators that after the second party, Brown was dropped off around 1 a.m. at a liquor store — about a half mile from her home. “But what we can gather is that the liquor store was closed,” says Hennes, who doubts that she was even dropped off there.

“We don’t have any witnesses that actually placed her at that liquor store,” Kathryn Torres, a senior deputy with the Ventura County Sheriff’s Office, tells PEOPLE.

Where Brown was killed also remains unknown.

“All indications are that she was murdered and then transported and left in Gorman, but we don’t know that,” says Hennes. “We don’t know where the homicide scene is.”

There is also no indication that the teenager, who lived with her parents and sister in a quiet, suburban neighborhood of Simi Valley, was abducted.

“We’re suspicious of the people that last saw her,” says Hennes. “And that’s where the original investigation ran into a lot of roadblocks. There was not a lot of information or cooperation at that time with that friend group.”

Detectives believe advancements in DNA technology might just give them the break they need to solve the case.

“When the crime scene was being processed, a lot of DNA samples were taken,” says Torres. “And we are now beginning to submit those again for updated processing. We have trace evidence we’re still processing that we are optimistic will lead us to a suspect DNA profile.”

As for who would kill the teen?

“Right now, we believe it was somebody that knew her,” says Hennes. “We don’t believe it was a drifter or some random person that just happened to come into town. We believe that Melinda knew the person that killed her, and we’re trying to prove that right now.”

Detectives hope that anyone with information about what happened will finally come forward.

“People didn’t want to talk back then, but maybe, we’re hoping, now 30 years forward … people have lived their life, and they have children of their own that maybe they would feel now is the time to come forward and say something,” he says.

Anyone with information about the case of Melinda Brown is asked to contact Ventura County Sheriff’s Major Crimes Unit at: (805) 383-8739 or email the Ventura County Sheriff’s Major Crimes Unit at: [email protected].

If you wish to remain anonymous, contact Ventura County Crime Stoppers at (800) 222-8477 or visit www.venturacountycrimestoppers.org to submit a tip via text or email.