AUSTIN (KXAN) – Seven. That’s the number of murders still unsolved, all people killed in Austin in 2014. It’s a number unusually high for this city. With those killers still on the loose, families of the victims can’t get justice and we’re all less safe as a result.

Thursday marked one year since the death of a well-loved teacher named Grace Chen. The motive and her killer are still a mystery.

“Grace was definitely somebody who exemplified who we all want to be in a human being,” said Austin Police homicide Sergeant Brian Miller. He opened the Grace Chen file for KXAN; it contains hours of interviews, a timeline of the case and photos of the crime scene.

“It was a violent death,” he said.

Grace Chen came to the U.S. from China for a better life. She treated her students at the Grace Language and Cultural Institute in North Austin like family. But where there once was learning, now an empty room sits for lease because just around the corner someone killed the teacher loved by so many.

“We haven’t found anybody that ever had anything bad to say about her,” Sgt. Miller explained.

Why, then, would somebody want to kill her?

“I wish I knew the answer to that– that’s something we’ve pondered for the past 6-7 months,” Sgt. Miller said.

“Its by far not a cold case,” Miller says, “It’s something we look at almost daily.”

Detectives say they did find DNA at the scene.

“There is evidence available, but it hasn’t been matched up to anybody, so that’s kind of what we’re working on right now,” Miller says.

But there are precious few other clues. Investigators know Grace left home the morning of February 19, 2014 around 9:30. She opened the school in the office space she leased on the second floor of the Galleria Oaks Shopping Center. And then, at 3:30 in the afternoon, a call to 911 reporting a woman’s body in the second floor restroom.

They think someone killed Grace two hours earlier. But they still won’t say how.

“We will get a suspect in the future and we need to have that information available to us so we can know if that person actually has details of the crime,” Sgt. Miller explained.

“Any idea at all what a motive would be?” KXAN Investigator Shannon Wolfson asked.

“We don’t have one at this point, that’s really why we’re asking for the public’s assistance,” Sgt. Miller says.

One detail making this case so complicated for investigators is that Grace’s body was found in a bathroom behind a locked door– only accessible to people who work in this complex and have a key.

“You often wonder why her and why in such a way? Why?” asked Amy Mok. “She certainly did not deserve to have her life ended in such a violent way. So I’m hoping APD will give us some answers soon.”

But there’s another person who desperately needs answers. Grace’s 22-year-old son, Yuchong “Jacky” Chen, and he misses his mother.

“It’s hard to start to describe her, but to me, she was the most important person in my life,” he told KXAN Investigator Shannon Wolfson. “That’s the only thing that matters to me right now because it’s been a year.”

“As long as the killer is not catched (sic) and the crime is not solved, just something in your heart, you just feel like you can’t really move on until they caught someone,” he explained.

Anyone with information about Grace Chen’s murder should call the APD homicide tipline at 512-477-3588 or Crime stoppers at 512-472-8477.

Grace’s murder is one of seven unsolved homicides in Austin in 2014 compared to just four still unsolved homicides in 2013. We’ve learned part of the problem in 2014 was 60 percent of the city’s 37 murders happened between mid-September and the end of the year. Detectives say that put a strain on the department’s homicide unit.

**Editor’s note: Suspects were arrested in June 2015 in connection to Robert Morales’ death.