Her Daughter Was Found Slain in Her Bedroom 20 Years Ago. Inside a Mom's Cross-Country Quest to Find the Killer

Brittany Phillips was an 18-year-old college student in Tulsa, Okla., when she stopped showing up to class, raising the suspicions of those who knew her.

She was last seen dropping off a friend at home after 8 p.m. on Sept. 27, 2004.

Three days later, on Sept. 30, officers responding to a welfare check — after a worried friend had reached out to authorities — found her strangled body in her second-floor apartment. She had been sexually assaulted.

In the two decades since, ex-boyfriends and strangers have been questioned, sex offenders have been investigated and DNA swabs have been taken — but there are still no suspects.

“This is the first anniversary where the case has been colder than when she was alive, because we buried her on her 19th birthday, Oct. 4,” her mother Maggie Zingman, 69, tells PEOPLE. “I never thought that she would be murdered. But then I never thought that it would be a cold case. And then never thought that I'd be sitting here at the 20th anniversary.”

This year, like she has for the past 18, Zingman is traveling across the country in her bright purple and pink KIA Carnival, which is adorned with large pictures of Brittany and a number to call for tips.

Her goal? To bring attention to her daughter's case in the hopes of finding the killer.

Zingman, a trauma psychologist who works with combat veterans, has dubbed her cross-country forays: “Caravan to Catch a Killer.”

“I want my daughter's case solved before I die,” she says. “I feel like the case dies with me. Brittany would kill me if I stopped, and she'd be doing the same for me.”

A college student who loved sports

Tulsa Community College student Brittany loved sports and music and had plans to transfer to Oklahoma State University and continue with her chemistry studies. She was hoping for a career in cancer research.

The last time Zingman spoke to her daughter was on Monday, Sept. 27 — the same day she was last seen dropping off her friend — when the teen had to go to urgent care because of allergy issues.

“She had been at a doctor's office, because she always had these allergy problems, and couldn't get in,” she says. “She was with a friend, and she told me, ‘I'm going to drop my friend off and then I'm going home.’"

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When Brittany didn’t show up for classes, a friend called police.

Inside the apartment, officers found Brittany dead on the floor next to her bed.

“There was some defensive stuff underneath the nails,” says Zingman. “She must have fought. My belief is that possibly he was waiting there, or he broke in after she slept.”

Despite interviewing hundreds of people, “nobody really was able to give anything concrete happening around the time this occurred,” says Tulsa Police Department cold case detective Jeremy Stiles.

'Maybe he's a serial predator'

In 2007, with no suspects in sight, Zingman began to wonder if the killer had moved on and was killing elsewhere. “Maybe he's a serial predator, maybe he travels along the highways, and he has been killing or raping people across the U.S.,” she says. “I really wanted to see if there were similar murders out there. That maybe a spouse, a sister, a detective would hear something familiar in my story.”

"I came up with this idea if I had something on the side of my car, something that people could see and automatically try to look me up and bring in tips, maybe that would be a way to get the story across the U.S," she says.

Over the last 18 years, she has traveled more than 300,000 miles across 48 states, passing out fliers at rest stops, police stations and traffic jams.

She’s gone through four vehicles, had cars break down in Oklahoma, Texas and Wisconsin, got lost in the middle of the night in Wyoming, white knuckled it down a Utah mountain in a severe rainstorm and navigated icy conditions in Washington State.

To pay for the trips, she’s lived without heat, water and air conditioning, struggled paycheck to paycheck and previously gone into debt. She says she has spent approximately $120,000 in her quest for justice for Brittany.

“It was worth it, especially in those early years because I was getting 12 to 16 [newspaper] stories each time I went out, and I'd go out twice a year,” she says.

Her caravan trips have generated multiple tips.

Stiles, the investigator, says, “We’ve definitely had people reach out and say, ‘Because of Dr. Zingman, made me want to reach out to you guys and here's what I know,' or ‘Have you checked into this,’ or whatever.”

Stiles adds, “I've yet to run across another victim's family that is as determined as Dr. Zingman, and she does an amazing job at getting the story out there and getting as many eyes and ears on it as possible.”

For Zingman, traveling the open road has been a way of coping with her grief.

“It's been how I survive, because beyond what the purpose is, the gifts, the connection, the hugs, the people honking at me coming down a mountain,” she says. “I have had such unbelievable experiences. I couldn't have survived this without these experiences.”

Although she remains hopeful that one day her daughter’s killer will be caught, her travels have become about connecting with other homicide cold case families.

“It's not about my daughter's case as much anymore,” she says. “It really is about wanting to reach out. Let me help you be a voice. Let me just say you're not crazy. Because that's what kills people.”

Tip complicates timeline

A possible lead in her daughter’s killing surfaced in 2023 when Zingman received a call from her ex-husband, who told her he found a birthday card that Brittany had mailed to him in 2004 to forward to her grandfather. The card had a post office stamp dated Sept. 29 — two days after police believe Brittany died.

“It was a stamp bought from a kiosk machine,” says Zingman. “If it was a regular stamp, that would be easy. Yes, it just sat in the mail bin for a while, but it was printed by the kiosk. This stamp having that date could change the timeline.”

Stiles agrees the timing is peculiar, saying it's "after what detectives thought more than likely the incident would've occurred."

Stiles adds: “I 100% can't say what I make of it yet, but it's unexpected, and odd.”

Right now, Stiles is hopeful that current genetic genealogy work on DNA found underneath Brittany’s fingernails will provide answers. “Obviously if that leads to an individual, that's definitely somebody who we're going to want to talk to next and figure out how they were involved,” he says.

Meanwhile, Zingman is getting ready for her next road trip around Thanksgiving.

She plans to hit Texas, Arizona, New Mexico, Nevada and California.  

“She was beautiful, and she was intelligent, and it just rips my heart out that the world lost her,” says Zingman. “But my car has been the gift. I know millions know her, because millions have seen her on the road.”

If you have any information about the murder of Brittany Phillips, please call Tulsa Crime Stoppers at 918-596-COPS or email homicide@cityoftulsa.org.

If you or someone you know has been sexually assaulted, please contact the National Sexual Assault Hotline at 1-800-656-HOPE (4673) or go to rainn.org.