Irma Gaither laughs as she remembers her daughter, Amber Stanley, who was shot and killed in her bedroom two years ago. No one has been arrested in connection with the crime. (Katherine Frey/The Washington Post)

The memories of her daughter’s last days play like a video on a loop in Irma Gaither’s mind.

Gaither remembers Amber trying on new lipstick they bought during a back-to-school shopping trip the first week of the 17-year-old’s senior year of high school. She remembers Amber sweetly looking up with a smile after Gaither told her the lipstick looked nice. And she remembers her last words to her daughter: “You’re so beautiful. I love you.”

Then Gaither stops the images. She doesn’t like to move ahead in the story. The part where a masked man kicks in the door of Gaither’s split-level house, heads for her daughter’s room and fatally shoots the teen in her bed.

“I just can’t understand, and maybe I never will understand, why someone would want to kill someone who is timid and meek — someone who had potential to do a lot in this world,” Gaither said.

Two years after Amber Stanley was killed, her case remains unsolved. Amber’s death Aug. 22, 2012, was the first of six fatal shootings involving Prince George’s County students that shook the community in a six-month span during the 2012-2013 school year. Amber’s case is one of two in which there have been no arrests.

Amber Stanley (Courtesy of Prince George's Public Schools)

On Friday, Prince George’s homicide detectives revisited the Kettering neighborhood where Amber lived, passing out fliers to regenerate interest in the case. Officials say the investigation into Amber’s death is far from a cold case.

“We believe that we are in the best position that we’ve been in in the past two years of this investigation,” said Capt. Jimmy Simms, head of the police department’s homicide unit. “We’re hopeful that as this investigation plays out, we will see a successful conclusion.”

Amber was an honors student at Charles H. Flowers High School, and she aspired to attend Harvard and become a doctor. She would have been a sophomore in college this year.

The memory of Amber’s death has stayed with the staff at Flowers, where she was a member of the school’s selective science and technology program. Principal Gorman Brown said losing Amber was like “losing one of our future leaders.”

“It was inspiring to see a young lady who was so focused, so composed and yet so down to earth and affable,” said Brown, who keeps a photo of Amber in his office along with pictures of other students who have died during his career as a principal. “It was evident she was on her way to doing great things.”

Brown said that although the students Amber would have graduated with are no longer at the school, teachers “still speak glowingly” about the girl who made cupcakes to share with classmates in the days before she died.

Irma Gaither talks two years after a masked man entered her home and killed her 17-year-old daughter. (Katherine Frey/The Washington Post)

Gaither said she has been touched by the school’s support of her daughter and family.

“She was a lovely person,” Gaither said. “She was nice and cared for people.”

When asked to meet to discuss her daughter’s case, Gaither didn’t want to do so at her home — a place she avoided for eight months after Amber’s death — choosing instead a nearby park. She arrived clutching photos of her daughter.

In the stack, there is a picture of Amber in a red-and-orange swimsuit at age 7 framed in white. She’s posing in the sand in Myrtle Beach, S.C., with a hand on one hip.

There is a picture of Amber at a family reunion, smiling with a cousin.

“There she goes posing again, always posing,” Gaither said. “She loved it.”

Then the images fast forward. Amber in a lacy dress walking down a runway. Although Amber had been modeling since she was about 11, her mother hoped the hobby would help Amber overcome some shyness and confidence issues in her teen years.

“This is from the fashion show she did right before she died,” Gaither said.

The night Amber died, she was getting papers and folders ready for school, her mother said. Gaither wasn’t home, but her oldest daughter and a foster child who had been living with the family were in the house with Amber, Gaither said.

About 10 p.m., Amber’s older sister heard a scream, Gaither said. Then the gunshots rang out. Amber’s sister ran upstairs, where she saw a masked man run out of the house. After that, silence.

“Nothing was taken,” Gaither said. “Nothing but my daughter’s life.”

Gaither toggles between competing narratives about what happened. At times, she believes Amber’s death may have had something to do with the foster child living in the family’s home at the time. The foster child was a teen Amber’s age, and the family had recently clashed with her over money and possessions missing from their bedrooms, Gaither said.

But Gaither also has her doubts: Was it just a case of mistaken identity, or was it someone just “being outright mean and wicked”?

“We would like to have justice done,” Gaither said. “But if it doesn’t happen, I’ll just wait on God to solve it.”

Police have not publicly stated a possible motive in Amber’s death, and Simms, the police captain, said the foster child, who no longer lives with Gaither, has been cooperative during the investigation.

Because Amber’s case is an ongoing investigation, police officials said they could not release new details. Detectives, however, are considering a “wide range of theories” and don’t believe Amber’s death was a random shooting.

The police department has invested thousands of hours in the case, which has been particularly challenging for several reasons, Simms said. Forensic evidence has been limited, and there wasn’t a true eyewitness to the shooting. Detectives have also talked to more than 100 possible witnesses and people of interest, some of whom have been interviewed two or three times.

“When you have to vet out that many interviews and that many leads,” Simms said, “it is painstakingly slow.”

Three weeks after Amber was fatally shot, another Prince George’s student was found dead on the side of the road. Central High School student Marckel Ross had been robbed at gunpoint and killed while walking to school. Four more students died in unrelated fatal shootings in the following months., including Aaron Kidd, who was shot outside a Forestville apartment complex. There have been no arrests in his case, either.

Losing one young person to tragedy affects schools differently than neighborhoods or other communities, said Brown, the principal at Charles H. Flowers. So losing six students in a single academic year was particularly tough.

“As an educator, you’re sowing seeds into the future,” said Brown, formerly the principal at the middle school Ross, 18, attended. “When those seeds can’t germinate because of senseless violence, it takes a piece of you with it.”

The man arrested in connection with Marckel’s shooting was convicted this month of second-degree murder and armed robbery. Travon Bennett, 21, is scheduled to be sentenced in October.

When Marckel died, Gaither said, all she could do was think of his mother: “I know how it felt.”

Every week, Gaither said, at least two or three people ask her about Amber’s investigation. She doesn’t always know how to answer, but she continues to replay the happy memories of her daughter in her mind. And as she sees cases of other young county students who were homicide victims come to a close, Gaither remains optimistic for Amber.

“So one by one, they’re getting them,” Gaither said. “There’s hope that maybe in this system, she’ll find justice.”

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